I haven't heard the LMS 18's yet, but if the price was right I would likely upgrade, as they share the same basket mounting layout, so they will drop right into my boxes. A guy will be coming with a LMS and we are going to do just that, swap one out for the GTG
I really like the Mal-X's, but there was a problem with my 3rd driver so I'm waiting on the replacement, came DOA
and then I'm going to get my hands on another amp to put my TC3000 Ti cone behind my couch for that extra kick in the gut.
Only problem with the 18" LMS's is that they need so much power, its a little rediculous when you look at your wallet. 3 of those would be freakin awesome, but the cost...