Hi!
Yes, the GP GEE BEE R-2 looks real nice and it flies just great. But forget it for a couple of years!
It demands so much more than a ordinary low winged airplane.
The problem is landings it. It is a real hot airplane to land.Flying is ok and so is take off, but landings are very difficult ...at least I think so after having flown mine for 10 times.
I have flown R/C for 30 years and last summer tried out the GB, doing an article for a R/C magazine here in Sweden and I assure you that despite having competed in pylonracing for many years I found it hard to do a nice landing with this airplane.
I have mine powered by a MVVS .91 two stroke which is much lighter than any fourstroke (300g) and despite the low weight (5kg), my GB was difficult to land.
Using a 1.20 fourstroke will add around 300-350g which will enhance the bad landing characteristics even further.
Pumped or not pumped doesn't really matter...both OS engines are very reliable.
What's importance flying this airplane is flying experience...that's more important than what engine you choose.
You get the best flying experience from competing!

Regards!
Jan K
Sweden