I have tried this on MFME 3.2 for the rescale option and it did not seem to be too much of a hassle to hit the reset button when the payout error came up (had 40 in the win bank as it automatically pays out any amount over the 40 pound mark). Basically what i am saying is that for those that can't see the full machine because the resolution is too high for their monitor, the mfme 3.2 and reset button option is better than nothing.
I have a 19 inch CRT monitor which can go up to 1600x1200 so i do not have any probs playing any of the emulations. I will be getting a 22 inch TFT sooner or later tho as it's all getting a bit too dark.
Just use 3.1. Thats the cure! Attached.