Curious as I have RB2 but have become increasingly interested in GH5 via the tracklist and amazon deals.
 
But I refuse to buy another plastic drumkit, I wont do it so dont say you needz them GHWT drums!
 
Is GHWT and presumably GH5 just as fun to play with only 4 notes instead of 5. Is it harder? or easier?
  
If people claim its rubbish I might not even bother with GH5

I have played several different Guitar Hero games such as World Tour, Smash Hits, and Metallica on the Ion drum kit and it seems fine. I don't have any way of making a comparison but yeah, it seems like it works fine. However I would recommend you don't buy GH games and just support Harmonix.   
 
I  <3  Harmonix          lol

well yesterday I played GHWT at a friend's house. he had RB and GH so I tried using the Rb set. It worked fine I think. I only played 2 songs. But I might get GH5 now since I have at least seen it works fine. I'm guessing it might be best for me since I've only palyed RB, so I dont have to adjust just to play songs that I like on GH5. Also I was thinking of getting the cymbals for RB2, so maybe a tiny advantage in favor of RB that it can have 3 cymbals, but so small.

I actually bought a full band GHWT kit for $100 at Wal Mart this past weekend, and am thoroughly impressed with the drums. Up until then I was using the RB1 kit, with some silencers for extra rebound. While initially I found the new cymbals hard to master (I was a hard/expert drummer in RB), they ultimately felt more realistic than the RB kit, albeit louder. Another plus to the GH kit is the size of the three main pads, they're bigger and quieter than the RB heads, and make drum rolls a breeze.  
 
I think both kits are great, though I've yet to put the World Tour kit through all of the paces and beat the shit out of it like I do on my RB kit. I hope to hell it stands up better than my three Red Octane guitars, all of which have either died completely (X-Plorer) or have unresponsive buttons due to that fucking detachable neck bullshit (WT guitar and Les Paul).  
 
Also, if you're used to the RB kit, the World Tour one is harder to play with simply because of the extra orange cymbol. You won't be used to having to hit an extra pad, thus taking some extra practice to use. I'm slowly adjusting to it myself.

Even though they're dodgy as feck, as I did have to get mine fixed, I do prefer playing on the GH drum kit to the RB one. 
 
I never liked the fact the Rock Band guitar buttons spread the entire neck. Felt weird. And the fact the strum never clicked; didnt feel like it was registering. 
 
So GH equipment is my vote. If only GH also had the DLC support that rockband has tho, life would be so much better.