I have about 3 OS's, including 2 flavors of 'untu, on each of two laptops. So far Ubuntu has been great at handle my predilection for extra partitions. This has been the case with 14.04, 14.10 and 15.04.So far.
I like lots of small partitions for backups - one around 700MB for CD backups, another another larger one for DVD's, one sized for my old 2GB flashdrives, maybe a 16 and a 32 for transfers with larger USB 3.0 flashdrives. It is easy to wipe unused disk space or entire partitions which is a great convenience and security enhancement.
I have never had trouble reading partitions with gpart, Partition Wizard and usually can mount partitions with occasional issues when permissions conflict. Some of my partitions are encrypted by one of my many Linux OS's and some are unencrypted.
My addiction to lots and lotsa partitions entered a new phase when I discovered that, as Rod Smith points out, Ubuntu spreads its boot and boot configuration files for Grub over two partitions. I had a problem getting my 'untu installs to show on the boot screen and discovered that it is easy to get grub to update via the recovery mode log in when I tried out installs with root, boot and home partitions rather than the more typical two-partition install.
Thus, with an average of three OS's per laptop, and an interest in going to a quad-boot, that would leave me with around 14 partitions counting the Windows Recovery partitions and my own boot partition backup.
I did have a problem with an Ubuntu-based distro(Mint) which, after some updates, could no longer read an encrypted drive. I had to reinstall and that issue leaves me wondering if, as i proceed with various updates, if Ubuntu might not be able to guarantee its performance with a very unusually complex network of partitions.
My question is whether I am courting disaster. Is there a signifgant risk that at some point my disc controller or some other system function will simply crash and burn when and if I add one too many small partitions? And, for that matter, is there some sort of major performance penalty I pay? So far so good, but I would heed the advice of those with different experience.