I have the 4 wheel version. It is very nice. Rolls easily and folds up very small. I've had it about 3 months.
Previously I had a 3 wheel Bag Boy that served me well for 15 years. It was quite a bit heavier, and didn't fold up as small, but it was a tank and lasted forever. The Caddytek doesn't seem as rugged, but I think it will still hold up fine.
GolfWRX has some discussions of the two, so you might go look there. If memory serves, the 3 wheel is considered easier to turn, while the 4 wheel is more stable and less prone to falling on a side hill.
I'm still learning the intricacies of the use of the 4 wheel versus 3 wheel. I can't say that I'd have a preference, they both do the job well.