LONE_WOLF, I have a budget priced wheel set I bought for an in-progress roadie build and I'm evaluating them on another roadie at the moment. Sora hubs, 32 14 gauge spokes and CXP22 rims, that after I spent some tuning time, have shown themselves to be quite reliable and I wouldn't hesitate for a moment to use for what you are planning. My key point is the quality of the wheel's build and your wheels may just need a quality re-build. From what info I found on the web, they're at least as good as the budget set I have.

You can use your current cassette on a different wheel only if the new wheel has a compatible free hub. Shimano 8-10S free hubs are the same with the possible exception of the 7800 10S. The extra weight of the trailer plus cargo will probably warrant lower gearing than what you now have, however. You may want to renew your brake pads also.

Brad