MyTraffic does have military flights included. Previously their models were a bit simple to keep framerates high, but with the latest version these have been updated as well.

See http://secure.simmarket.com/mytraffic-x-pro.phtml

Does anyone know if REX works with DirectX 10, or am I asking a stupid question?

Yes it works with DX10, and it comes with water textures that are specifically optimized for DX10.
There are freeware texture sets available as an alternative to REX, but REX offers so much variety that it is well worth the purchase IMO.

If you want to use DX10, be aware that there may be issues with older addon aircraft (usually AI traffic). UT2 should be fully DX10 compatible, I don't know about the others.

After trying XP so many times and multiple unistalls/installs of FSX, i sat down and took my time to tweak and tune FSX one last time. I purchased all of the above that i already didn't own + ORBX scenery. Installed and tweaked the FXAA Injector ....

It's like a new sim!! What was looking and feeling it's age as standard install, now holds it's own. and better than i imagined.

Thanks Johan and everyone else in this thread

Well I got REX and I'm beginning to understand how it works, and loving it. Now I wonder whether UTX or GEX comes next.

It doesn't matter what order you install GEX and UTX and you don't have to buy both at the same time. The simplest procedure is to install GEX first, since it just replaces the stock textures, and then install UTX over that since the setup utility asks if you have GEX as well. If you get UTX first, you'll just have to remember to enable UTX's GEX-compatibility feature at a later time.