Yea, the better one is Rebug 4.21.1 REX. I tried Rogero 4.30 and its so buggy I only had it on for about 10 mins. Rebug is so easy. To install goto Recovery Menu and install. To downgrade just install Rebug 3.55.1 REX. Easy. Also this Rebug has a lot of the features QA mode does so I really like it.
With UFC 3 I do have an install problem. It is installing but it did stay on 14% for about an hour, now its in 18% and the HDD is flashing so I'm guessing its installing but its taking a really long time.
Try that eboot in 3.55 before updating. I did have it working but it did lockup after a few mins.