The TRF502X is an awesome buggy. I also do not have a 511, but compared to my TRF501X, the TRF502X feels 100x more comfortable to drive. It was easy to setup. Feels very quick and agile on the track. Jumps nicely. And, builds like a TRF! I would highly recommend the TRF502X.
The lack of spares is a bit scary (bulkheads & gear boxes). I'm always dodging short course trucks and 1/8 EP buggies on the track. I'm afraid one day I won't be so lucky, and I'll get flattened by a 1/8 buggy going the wrong way down the straight.
