There's no difference in 6.20 PRO and 6.60 PRO. Use whichever suits you best. 6.20 has an option for a permanent patch, but I've heard that it slows down the boot-up on the go (compared to the 1k/2k/3k psps) so I'd go with 6.60.
You can downgrade to 6.20 from 6.60 anytime you want.
Also, you should contact a mod or admin to delete the extra two threads you made (?)