I experimented with posing the jeans model a bit, to see how it deforms in extreme situations and that there is no strange stretching going on.
I must say I'm pretty satisfied. It behaves pretty well. There are however a few imperfections.
As you can see it's mostly texture problems. The crotch area and the seam on the back seems to be heavily affected by stretching and gets smeared out pretty obviously.
I admit that the texturing in the crotch area is a bit of a problem. That's the area where my texturing and UV mapping could be improved most. Maybe a quick fix there is to remove any obvious patterns (which are barely visible anyway) and keep it blue so it's a lot less obvious if it stretches out.
About the problem with the seam in the back, I guess it's because that seam is put right on top of the lines that divide the pants in half. There is probably a lot of deformation going on in that area when the left and right of the body are posed differently. Maybe a fix would be introduce a little more geometry there, so it can deform a bit smoother. I'm not really sure.
Another remark is that the AO shadow between the legs that's been baked into the texture might not be very realistic when the legs open wide. Normally the shadow would disappear because the other leg is not casting a shadow on it anymore. Therefore, if you intend to use the jeans model for offline rendering (eg. in Blender) you might want to use the regular diffuse texture without ambient occlusion shadows baked on.
You could in fact calculate the ambient occlusion for every frame just by enabling it in your render process, which would calculate correct shadowing when the legs open.
For a game, however, this would probably suffice, and is a good default to have (also for viewing within MH). Of course you could use a SSAO shader or even blend the AO map in and out together with walking animations and such. I've read that they used this blending method in Uncharted 3 to make it look like the folds in Drake's clothing moved when he runs.
This is up to you.
On the whole, I think it's pretty useable right out of the box. Just export it out of MH along with your character and you're good to go.