Miniatures vary- but we estimated the infantry at a very light 15mm.
I have to disagree here. I originally bought some 15mm to go with my Clix figs and they didn't match at all. The MW figs are definitely 10-11mm. The official metal Battletech infantry figs have been prone to some scale creep and in many cases are approaching 8mm. That, plus the lower importance of scale in the board game means that there are quite a number of BT players who have used the clix infantry despite the scale differences.
Here you can see a 15mm infantry next to the large 10mm battle Armor.

Doesn't seem quite so bad, but now here's the 10mm MW battle armor next to a standard 10mm MW infantry trooper.

All this to say you can sneak some of the 10mm battle armor and suits into 15mm, but 15mm infantry towers over 10mm MW infantry.
The mechs and ground units are all fairly close to 10mm but there are some outliers.
-The large transport helicopters, a few of the ground vehicles and a couple of the mechs are pretty darn close to 6mm.
-The Targus mech especially but also some others would work in 15mm. Especially those that don't have the aircraft style cockpit canopies. There are also some battle Armor that would work well.
Conversions of MW into miniature gaming traditionally go very well.
This I do agree with. After buying a number of HUGE lots of Mechwarrior clix and divvying them up by faction, our club decided to do nearly all our small scale sci-fi gaming in 10mm. Most of us didn't even repaint the figs, we just rebased them.
We've used them in:
Mech Attack: Imagine battletech with 1/10th the rules that plays in 1/4 the time and you've got some idea. A really fast and fun game that is also quite customizable (buildable units) and flexible. Also cheap. Works best with less than 10 units per player.
Alpha Strike: The Battletech game of big battles. Also, alot simpler and faster playing than battletech. Works best with more than 10 units per player
Panzer8 Sci-Fi: Beer and Pretzels sci-fi mass battle. 2 pages long and it's free.nWe made a few minor tweaks and reorganized and edited the ruleset to make it easier to understand.
You can get our club's version here:
http://www.dakkadakka.com/dakkaforum/posts/downloadAttach/140892.pageAnd the Force list we built :
http://www.dakkadakka.com/dakkaforum/posts/downloadAttach/140893.pageSkip the first post, but scroll down and you can see most of the games we've played with mechwarrior clix figs here:
http://chicagoskirmish.blogspot.com/search?q=mechwarrior