I dont have access to one to check. Felt hasn't seen 3d to verify. But longer stem has 2 cable stopd so should be able to run inner cable to front brake.
I was hopeful this might be a future option for a Felt IAxx stem replacement but alas, you recommend 33mm of steerer to clamp to and if I'm not mistaken the Felt IAxx steerers have been cut to 29mm for their stock stem.
So, either I have that dimension wrong or you've already ruled out most people's Felt IAxx as a candidate for this stem. A shame as it does look like it would have been a very interesting option.
If someone in the Philadelphia area wants to stop by with an IAx to try if it works, feel free to PM me. Can the effective IAx steerer be increased with an ultra low duster cap, or by removal of the duster cap? I'm not too familiar with that stem/steerer junction