I have GDE and Home++. I tried GDE out for about a week, and I still try it for a bit after every update. In terms of speed and stability it just does not compare to Home++. I was trying to show off my droid to a friend who was thinking of purchasing and was running GDE at the time. Her husband was watching, and I agreed with him, that the phone looked a bit sluggish. I was like just a sec, switched to Home++, and asked, "how bout that?" vastly improved their impression of the phone.
GDE is incredibly sluggish after unlocking my phone. It speeds up a bit if I'm using my phone actively for awhile, but when I need to open apps quickly is right after I unlock my phone. Having to wait for the screen to draw so I can open Maps or Email is just silly. It also force closes frequently, and occasionally is totally unresponsive.
GDE is for flash. If you don't mind waiting for apps to load, the screen to rotate, and dealing with force closes, then you might be able to deal with GDE. It honestly does look great, and I was enamored enough with the visuals for a short time that I was willing to put up with it, but I need my phone to be ready to go when I am. I will applaud the developer though for being very active and providing updates regularly. It has sped up quite a bit since I first installed it a month ago via updates, but it still has a lot of problems that reduce its functionality. I'm aware it is in beta and hopefully the developer can iron out all the bugs. However, I don't believe in paid betas, which is what GDE is.
Home++ is fast, minimal, offers up to 7 screens, and has the wraparound workstation. It supports animated widgets out of the box, which as far as I know, no other home replacement does. Also the power strip provides more function than any launcher for the other home replacements. Each button has short press and long press functions, very intuitive. Holding the app launcher button takings you to Application settings.
Home++ is still in beta, and is incredibly fast and functional. The design is minimalistic, and not skinnable(at the moment), but the developer is very active with updates and may add theming elements in the future.
My recommendation, try Home++ first. If you're really curious about GDE, DL it try it out, return it if you don't like. Its only $2 bucks or so.