The stock 92744 that comes with the MX-3X is the same stock rx that came with my M11X,

I had the same question when I got my M11X and everything said it wasn't good for unregulated LiPo use. Contacted Airtronics about that very thing and found that it would work. It could get a little warm though. I have that Rx in my Truggy right now and haven't had any issues, though the only thing in my Rx box is the Rx and a little foam to keep it from moving around and My Lipo is mounted in the forward batt. box if that makes any difference.