It was bugging me that I didn't plug in total numbers for spirit and int when calculating the approximate spirit and int mana regen from new pieces of gear for my Ulduar gear list. Some pieces were coming up with totals of 0 MP5, because they would lack spirit or int. So when you plug the stats from JUST that gear into the fancy-dancy mana regen equation, it would equal zero.
86 = 68 * 1.15 * 1.10 * 1.02
Spi/Int Mana Regen In-Combat = ((SPIRIT)*0.003345*SQRT(INT)*5 + 0.001)*0.50 MP5 = ((86)*0.003345*SQRT(0)*5 + 0.001)*0.5
Effective mana regen includes raw MP5, replenishment, and regen from spirit and int. Mana regen is a rough estimate - but it should remain more or less proportional when comparing gear. It is a rough estimate since spi/int regen will vary slightly depending on the amount of spirit and int you have currently. I assumed 1250 spirit and 1050 int raid buffed before equipping the new gear. I went with lowish numbers, because you are taking off the piece of gear you are about to replace.
Spi/Int Mana Regen In-Combat = ((1250)*0.003345*SQRT(1050)*5 + 0.001)*0.5Before Gloves = 339 MP5
Spi/Int Mana Regen In-Combat = ((86+1250)*0.003345*SQRT(0+1050)*5 + 0.001)*0.5After the Gloves = 362 MP5