
SMP is by far the most realistic (and also the most stable). I own SMP, 圎 and UWXP, so I have tried all of them at length. So, whenever I want really high frame rates over any scenery, however complex, I use UWXP. UWXP offers a great alternative but again, the 2D textures limit the realism. The default XP clouds are OK, but suffer from the limitations of 2D textures. The only real competition for a full-scale weather environment at the moment is 圎nviro. Clouds and scattering are particularly well done - although it would be nice to have something other than cumulus.

SMP provides a very good rendering of the atmosphere. There is no issue (or difference) in using the Steam edition, as you found out with SMP.

RWC is a plugin, not a separate program, so it seamlessly integrates with SMP. If you want to go one step further, FSGRW is very good.

It does a great job of displaying real-world weather in real time, using X-Plane's default real world weather. If you haven't already purchased it, I would recommend RWC.
