Are you guys sure the mana pool is integer? Or that the addition there is integer?

I mean, it's quite likely that the mana pool is floating point number just like pretty much every other stat related value is in SL.

What I mean by this is that it shouldn't matter much whether your mr is +1.97 per sec or exactly +2 per sec other that the 2 looks different in the stat page.

My 323 mana bar fills up in roughly 220s with my 130 int (lev 26) and +1 mr, compare that to your +2 and if it's not half then the threshold is for stat displaying only (just like damage
and other stats are). I can't verify that right now since I've dumped all int boosting gear. But I'm reasonably certain that the sunwalker suit I had (which must have taken my int above the threshold and thus mr to +2m/s) did not regenerate mana twice has fast as the explorer suit (which leaves my int to 130) does.