That's at 0.6 or 0.06in DOC with that quarter inch cutter?
I'm all for cheaper bits, at this point actually I'm willing to pay anything if it will remove material faster, really..for production's sake. I can see that a 0.25in bit wouldn't bog the machine down but I am getting to the max cutting ipm on my machine as well, it's 110ipm I think, and I'm running the half inch bit at 100-103ipm so the only real place to go from here is more WOC or DOC, or both, which I'm having a hard time grasping a 0.25 or 0.375 bit will take more of than a 0.5in bit .
I do agree the Tormach 1100 is being pushed pretty hard and probably can't even run a half inch bit optimally, but I'm not sold on more MMR from a 3/8 or 1/4in end mill at any feed/speed/DOC/WOC combo than a 1/2in end mill.
I would live to be proven wrong, like you said, they are cheaper and for my application using a smaller but will leave less rest material to remove so it would be fantastic if it were the case.
Here's a shout if the parts I'm making with this recipe of 1/2in roughing and 3/16 finishing.