kenji87, welcome to the world of modified cameras. All thanks to our good friend who made it come true, right?

I have no experience in how 17-40mm perform in IR, but I know my 16-35mm cannot make it in the hotspot department.
But I am sure you can look for someone who has the 17-40mm, or even perhaps you can go down to your usual friendly neighbourhood camera shop where you buy 99% of your equipment from, and ask them to let you try out one before you decide.
A good example is our good brother LowLights who did it together with our good brother SurrealDreamWalker in the very recent thread where they tested a few (note, a few, not only one... hahaha...) lenses.
But after saying all that, I am sure there must have been some experienced senior members here who have tried out the 17-40mm on their IR cameras whom may give us some more feedback.