So I've got the new versions of Reason and Record now, and am just getting out of the "whoa" phase. Gotta say, Propellerhead did a great job with the Kong Drum Designer. The new machine does for drums what Thor does for synths. I'll still be making drums with Thor for the refills, at least until most people have upgraded to version 5, though I may program them in Kong as well and release v5 refills too. It seems like refills made in this version with the new refill packer will work in reason 4 as long as the new features aren't used, but I'll be doing a bunch of testing to make sure before I release the next refill--which I'm in the home stretch on right now. Lots of drums in this one. One more thing I'll have to test out is whether there can be a folder of v5-only instruments within a refill and it will still be able to be opened in v4, just with those specific instruments being unusable until Reason is upgraded. If not, we'll figure something out.
In any case, the instrument emulations are nearly done for the next release. Off to do more right now.