I haven't yet used the 10 watt package, but I use the 15 watt UV and Dental blue ones pretty often at work.
What's good:
1. Packaging on the 15 watt unit is really nice (+/- leads mounted on a flexible ribbon).
2. Thermal resistance to the base is really, really low, so just mounting these on...
I've done a lot of work with the 405 nm UV LED modules from LEDengin. Their largest is around 3W emitted power (15 W input). They run about $75 each, however.
I'm looking for similar units (in the 0.5W and up range) with flat lens packaging, since I'm trying to focus the power down to a...