murphy, the Winchester-import TM1's, the ones with the tapered rib, shoot higher than the Ithaca ones, generally, at least they were meant to as you can see from the increased pitch of the rib. If you like a flat-shooting gun, the Winchester may not be for you; at least, it wasn't for me.
Any one of either kind and TMX too must be suspected of so called "choke work" now and so must be both measured with a bore gauge and shot to be sure what's going to happen.
If your present TM1 is a Winchester and you like where it shoots, I'd not expect any TMX to suit you. If yours is an Ithaca, I'd think it would likely be a good match. Excluding, of course, "choke work" on either one or both, the effect of which is completely unpredictable.
Neil