Is anyone else who has played blades for a long time having trouble hitting the T100 irons?

I've tried to hit the T100 several times, but always get the same result. I just can't seem to find the sweet spot on this iron. It's not that my swing is off. The last time the "fitter" tried to get me to hit the T300 as he thought it might help me. I proceeded to to get my 7 iron (MB) out of my vehicle and hit a dozen between 165 and 168 yards with a 3 yard draw down the middle. They didn't have a MB demo head so he took the shaft out of the T100, put it in a CB and I hit it just fine. This doesn't make sense to me. The only thing I can think of is that after hitting blades for so long I am programmed to hit the ball out the hosel of true center and the T100 sweet spot just isn't there.