I have never heard of Reaper so I can't comment on that, but I've purchased both the first DFH and DFHS. The first DFH is much cheaper but its pretty limited compared to DFHS. DFH is basically just a sample library of a drumkit recorded extremely well with no processing. You use a soft synth like Battery to trigger the sounds via midi.
DFHS is a fucking godsend. There are actually a lot of proffesional bands that have used it in place of a real drummer with astounding affect. For example, Meshuggah used it on their latest album, and their drummer got an award in one of the drum magazines (either DRUM or Modern Drummer, I can't remember which) for his drumwork. Basically they were fooled into thinking they were real drums.
The advantages of DFHS over DFH are numerous. You have something like 13 snares, 5 drumkits, 60 cymbals, etc. and theyre all multisampled so you never get that machine gun affect that happens with alot of fake drums. also it comes with its own VST plugin, which wont work with earlier versions of Sonar unless you have a VST wrapper, as the earlier versions of sonar only support Directx plugins directly. You can also control the amount of bleed from all of the other mics independently, which you can't do with a real kit, but when rendering the wav files down, mixing them is alot like mixing a real kit. Be warned though, that you'll need 40 GB just to install it, and to run the thing in real time you'll need a lot of RAM. I highly recommend it though.
