Tensers Transformation

[dzidek1983]

Currently we have this:

Tesner's Transformation: You gain the following benefits:
+4 Strength, +4 Dexterity, +4 Constitution, +4 Natural AC, +5 Fortitude saves, Proficiency with Simple and Martial Weapons,
100% spell failure,
attack bonus equal your hit dice minus your current BAB.
You do not Polymorph anymore.

my question is...

lets say i have a lvl 30 mage so the HD=30
he ends with BAB16
so he should get a +14AB bonus

lets presume i end with 26AB unbuffed
i can cast at least couple of spells that give bonus to AB (GMW, GHeroism, Bulls, Haste, etc.) for about +12AB
so i have 38AB and cast Tensers for +14 for total of 52AB for 6 min extended
are my calculations correct?
does it make it the best leveling spell for the mage? better then polymorph?

and my 2 question

if ihave a red wizard transmuter he will get a min 35 CL (possible 38 with ok on rules right now) in transmutation
in a happy scenario will i get a nice 38-16 = 22 AB bonus for a total of 60 AB modifier for 6 minutes extended?

[DM Carebear]

20 attack bonus is the hardcoded cap.

[dzidek1983]

total or from one spell?

[Eldebryn]

Also your CL doesn't make this spell stronger, CL only makes it last longer. For the AB increase it uses your HD which has nothing to do with CL.

[Luna]

total or from one spell?

Is that a trick question.