You have a high dex, precise shot and point blank shot, and they are ranged touch attacks. So hitting shouldn't be too much of a challenge, though it's an issue that will sometimes come up. Fortunately, it's not a hit or miss tactic - you are shooting 6 rays a round, and can afford to miss with one without it being a huge problem.
If you use a 25 point buy and have a high dex with 26 Int at level 12, then constitution is very low.
17 base Int costs 15 points. 3 level ups into intelligence plus a +6 circlet gives 26 intelligence.
14 base Dex costs 6 points.
12 base Con costs 4 points and exhausts the attribute points.
Base stats:
8 Str, 14 Dex, 12 Con, 17 Int, 8 Wis, 8 Cha
The BAB is only +5 so it seems like the build might miss humanoid opponents on rolls other than 1. Even with Gloves of Dex +4, the attack bonus outside 30 feet is only +9. A fighter in full plate with 12 dex and a +1 ring of protection is only hit 90% of the time. That brings the first round average damage from 192 to 173. It brings the round 4 average damage down from to 75 to 68.
At this point the build has 36000 gp remaining. It has spent 36000 + 16000 on Int and Dex stat enhancers.
Saving throws are pretty good actually, though a bit lopsided with that Iron Will in there.
Does incantrix have a good fortitude save? If not, I think the fortitude save would be a base of +3, one less than a standard wizard. I don't have the book with incantrix. Does it get an ability to mitigate a low fortitude save?