I haven't used a MLST personally, but my dad had a RC18T with oversize monster wheels. It had serious trouble going through anything besides freshly cut grass.

It also doesn't take much to upset the chassis of a 1/18th scale vehicle, they simply do not have the weight behind them.

After I moved up to 1/10th scale I haven't looked back. The larger size and weight of the Emaxx allows it to go over pretty much any obstacle.

I was in almost the exact same position as you a bit over a year ago, and I got an 18t, only to find that it would not do what I wanted it to do. My dad got an Emaxx a couple of months ago, and I built an E-Revo. Needless to say, my 18t is now for sale. Just keep in mind that it will be more expensive. Make sure if you get the Emaxx, to buy high quality batteries, I bought some Tenergy batts from ebay, and they lasted about 2 months before becoming useless. Look for either IB(Intellect), GP(Gold Peak), and I've also heard that EP makes good batteries.

Greg