The hub should be okay as long as it is a 32h or 36h item. Mavic CXP22 or Sun CR-18 rim with 2.0mm DT Champion spokes/nipples at 3x should yield a very strong wheel if properly built. 250 lbs is a lot of mass for the average non-custom built wheel.

Try to spread apart the two spokes (cassette side) at their crossing with one hand. You should encounter very stiff resistance before the spokes lose contact if the wheel is properly tensioned. This technique will not work if the wheel is radially laced.

I personally would not let this shop rebuild a new wheel since they did not properly set you up with the right set of wheels. Performance is usually located in a major city so you shouldn't have any problem finding a good wheelsmith.

http://www.treefortbikes.com/product...R-18-700c.html

http://www.chainreactioncycles.com/M...?ModelID=17150