First of all, let's take a look at the street price of the GEM - Yikes! Nearly $2000 MORE than street price on a G70!

Now LISTEN to the demos....... subjective, I know, but the GEM sounds wooly and reverb-y, Roland's demos for the G70, punchy and clean (if still a bit reverb-y for me!)

So what do you get for an additional $2k? Mostly the ability to record audio (at up to 16bit/44k, which is hardly pro, now) and playback audio. Not enough, I fear. The PA1Xpro will do audio at much less than the GEM.

Anyway, to return to your original question, I honestly think that if you have had Roland Discover and are used to Roland's way of working, go with the G70 - I love mine (had a G1000 prior) and the Korg might be your cuppa tea if you REALLY need sampling and audio playback, but to my ears, the Roland's styles are more natural, and the ease of modifying them is outstanding! And the Korg will take a LOT more work to make GS SMF's sound good!

BTW - Summer NAMM seems a total yawner - nothing of much interest to us here.