Would this be worth it in terms of noticable gain?
As a boot and main application drive you will get noticable benefit especially if you use large applications or have a lot of software loaded at startup. I've got a PC with WD Blacks in RAID 0 (full disk imaging for backups
) and another similar PC with an Intel SSD as the boot/application drive, and the SSD PC is much snappier to use and quicker to start.
Would reliability be sacrificed much?
In theory SSD should be more reliable and can 'fail' in a read only mode, but time will tell how SSDs will actually fail in practice. I never chance anything (including accidental deletion) and keep multiple copies of everything so I would just use one of the WD Blacks for backup and the other for additional data.