Yes please... get an LMT, chopped carry handle, or any other BUIS you like. One of my shooting buddies got one with his AR, and while it is a nice A2 sight, devoid of the tunnel effect of a carry handle, it's severly limited in it's application. Anything you put on it besides the Aimpoint M2 is going to be too tall to be comfortable. You might as well be mounting an optic on top of a carry handle.
Get the LMT. IIRC it's now CHEAPER than the RRA TCH anyway.
With that, you have the OPTION of using a tall optic directly on the flat-top rail (EOTech, OKO, HAKKO), a short optic with a 3/4"riser,(most tube red-dots with built in mounts) a medium optic with a 1/2" riser (most red dots that require a ring) etc. It's customizeable to your tastes rather than just the one height that you're stuck with.
On the other hand, if you already HAVE the RRA TCH, by all means DON'T throw it away. Try and sell it on the EE (for a loss of course, the resale value of them is low) or contact Kurt at KKF over in the industry forum and see if he could chop it to a BUIS. He does carry handles for $35, and he does an EXCELLENT job. I don't see why he couldn't do a TCH too.