By the way, SS is currently working on eCS 2.x which is supposed to allow for bootable JFS drives. If they ever manage to get that one working, then I would consider switching myself from WSeB to eCS.
I've used JFS since Aurora, but keep in mind that there are limited recovery tools for JFS, so a really good backup strategy is mandatory. There is JRescuer http://ecomstation.ru/jrescuer
but I've never used it. Basically because I've never had a problem. That said a big cache and a journaled chkdsk are very useful. And supporting up to 2TB filesize/partition size is necessary these days with 200+ GB drives.