It's up to debate whether fakeraid has any performance advantage over Linux Software RAID (MD) since it's still delegated to the CPU. The best advantage it has is sharing the volumes between multiple OS that also support this metadata e.g. Windows. Depending on the actual fakeraid metadata format, it may be portable to other systems.
asr : Adaptec HostRAID ASR (0,1,10) ddf1 : SNIA DDF1 (0,1,4,5,linear) hpt37x : Highpoint HPT37X (S,0,1,10,01) hpt45x : Highpoint HPT45X (S,0,1,10) isw : Intel Software RAID (0,1,5,01) jmicron : JMicron ATARAID (S,0,1) lsi : LSI Logic MegaRAID (0,1,10) nvidia : NVidia RAID (S,0,1,10,5) pdc : Promise FastTrack (S,0,1,10) sil : Silicon Image(tm) Medley(tm) (0,1,10) via : VIA Software RAID (S,0,1,10) dos : DOS partitions on SW RAIDs
It may be possible for one to migrate from a fake raid metadata format to the md metadata format.