I'm going to risk answering this question since I now feel I have collected enough information on this issue. Basically downgrading to Nautilus 3.4 seems not to be an option at this time; it was coded for an earlier version of GTK, thus it wont compile on Ubuntu 13.10. The only practical way is installing a different file browser.
As it happens, Nemo is actually a fork of Nautilus 3.4 that has kept all the features of the latter (adding a few more). I've been using it since yesterday and the interface is almost the same, a seamless transition for the user. Thus installing Nemo is not very far from downgrading to Nautilus 3.4. I haven't done it yet, but it is possible to set Nemo as the default file browser.
All features I used in Nautilus 3.4 seem to function properly in Nemo (e.g. Connect to Server). The only exception at this stage is the integration with RabbitVCS, there's a package available but non functional at the moment. Since RabbitVCS doesn't work on Nautilus 3.8 either, it is not a regression.
Update II: There's no need to install Cinnamon, just install the Nemo package:
sudo apt-get install nemo
Update I: Nemo's appearance can be tweaked into something closer to the default Unity style. Open its css file:
sudo gedit /usr/share/themes/Ambiance/gtk-3.0/apps/nemo.css
And then replace all contents with the following:
.nemo-pathbar-button,
NemoPathbarButton {
background-image: -gtk-gradient(linear, left top, left bottom,
color-stop (0, shade(@dark_bg_color, 1.1)),
color-stop (.3, shade(@dark_bg_color, 1.1)),
color-stop (.7, shade(@dark_bg_color, 0.90)),
color-stop (1, shade(@dark_bg_color, 0.80)));
border-color: shade(@dark_bg_color, 0.7);
-NemoPathbarButton-border-radius: 3px;
}
NemoPathbarButton:active {
background-image: -gtk-gradient(linear, left top, left bottom,
color-stop (0, shade(@dark_bg_color, .8)),
color-stop (.3, shade(@dark_bg_color, .9)),
color-stop (1, shade(@dark_bg_color, 1.0)));
border-color: shade(@dark_bg_color, 0.7);
}
NemoPathbarButton:hover {
background-image: -gtk-gradient(linear, left top, left bottom,
color-stop (0, shade(alpha(@dark_bg_color, 1.4), 1.25)),
color-stop (.3, shade(alpha(@dark_bg_color, 1.4), 1.25)),
color-stop (.7, shade(alpha(@dark_bg_color, 1.4), 0.95)),
color-stop (1, shade(alpha(@dark_bg_color, 1.4), 0.85)));
border-color: shade(@dark_bg_color, 0.7);
}
NemoWindow * {
-GtkPaned-handle-size: 1;
}
NemoDesktopWindow GtkWidget {
background-color: @transparent;
}
.nemo-canvas-item {
border-radius: 4px;
}
/* desktop mode */
.nemo-desktop.nemo-canvas-item {
color: @bg_color;
text-shadow: 1px 1px alpha (#000000, 0.8);
}
.nemo-desktop.nemo-canvas-item:active {
background-image: none;
background-color: alpha (@bg_color, 0.84);
color: @fg_color;
}
.nemo-desktop.nemo-canvas-item:selected {
background-image: none;
background-color: alpha (@selected_bg_color, 0.84);
color: @selected_fg_color;
}
.nemo-desktop.nemo-canvas-item:active,
.nemo-desktop.nemo-canvas-item:prelight,
.nemo-desktop.nemo-canvas-item:selected {
text-shadow: none;
}
/* browser window */
NemoTrashBar.info,
NemoXContentBar.info,
NemoSearchBar.info,
NemoQueryEditor.info {
background-image: -gtk-gradient (linear, left top, left bottom,
from (shade (@cluebar_color, 1.02)),
to (shade (@cluebar_color, 0.98)));
background-color: @cluebar_color;
border-bottom-color: shade (@cluebar_color, 0.92);
border-radius: 0;
border-style: solid;
border-width: 0px 0px 1px 0px;
box-shadow: inset -1px 0px shade (@cluebar_color, 1.02),
inset 1px 0px shade (@cluebar_color, 1.02),
inset 0 1px shade (@cluebar_color, 1.04),
inset 0 -1px shade (@cluebar_color, 1.01);
}
NemoTrashBar.info:backdrop,
NemoXContentBar.info:backdrop,
NemoSearchBar.info:backdrop,
NemoQueryEditor.info:backdrop {
background-image: -gtk-gradient (linear, left top, left bottom,
from (shade (@cluebar_color, 1.01)),
to (shade (@cluebar_color, 0.99)));
background-color: @cluebar_color;
border-bottom-color: shade (@cluebar_color, 0.92);
box-shadow: inset -1px 0px shade (@cluebar_color, 1.01),
inset 1px 0px shade (@cluebar_color, 1.01),
inset 0 1px shade (@cluebar_color, 1.02),
inset 0 -1px shade (@cluebar_color, 1.0);
}
NemoSearchBar .entry {
}
.nemo-cluebar-label {
font: bold;
text-shadow: 0 1px shade (@cluebar_color, 1.06);
}
.nemo-cluebar-label:backdrop {
color: mix (@fg_color, @cluebar_color, 0.2);
text-shadow: 0 1px shade (@cluebar_color, 1.02);
}
#nemo-search-button *:active,
#nemo-search-button *:active:prelight {
color: @dark_fg_color;
}
NemoFloatingBar {
background-color: @info_bg_color;
border-radius: 3px 3px 0 0;
border-style: solid;
border-width: 1px;
border-color: darker (@info_bg_color);
}
NemoFloatingBar .button {
-GtkButton-image-spacing: 0;
-GtkButton-inner-border: 0;
}
/* sidebar */
NemoWindow .sidebar,
NemoWindow .sidebar .view {
background-color: shade (@bg_color, 0.95);
/*background-color: @bg_color;*/
color: @fg_color;
text-shadow: 0 1px shade (shade (@bg_color, 0.95), 1.04);
}
NemoWindow .sidebar .frame {
border-width: 1px 0 0 0;
border-style: solid;
border-color: shade (@bg_color, 0.86);
border-radius: 0;
}
NemoWindow .sidebar:backdrop,
NemoWindow .sidebar .view:backdrop {
color: mix (@fg_color, shade (@bg_color, 0.95), 0.2);
text-shadow: 0 1px shade (shade (@bg_color, 0.95), 1.02);
}
NemoWindow .sidebar row:selected {
color: @selected_fg_color;
text-shadow: 0 1px shade (@selected_bg_color, 0.8);
}
NemoWindow .sidebar row:selected:backdrop {
background-image: -gtk-gradient (linear, left top, left bottom,
from (shade (shade (@bg_color, 0.95), 0.94)),
to (shade (shade (@bg_color, 0.95), 0.86)));
border-top-color: shade (shade (@bg_color, 0.95), 0.88);
color: @fg_color;
text-shadow: 0 1px shade (shade (@bg_color, 0.95), 0.96);
}
NemoWindow .pane-separator {
background-color: shade (shade (@bg_color, 0.95), 0.94);
border-color: @dark_bg_color;
border-style: solid;
border-width: 0;
box-shadow: none;
}
NemoWindow .pane-separator:backdrop {
background-color: shade (shade (@bg_color, 0.95), 0.96);
}