Just picked my Ru 251, paid for 75% crew, and being into the 3rd battle - a Mastery Badge. It could be that a Lucky thumb was deserved here, but in any case, it was a nice surprise for me. I did make another one yesterday, 2.8k damage, 3 or 4 (not sure now) destroyed tanks, and over 1k damage with my spotting. So again, it was close to 4k in total.
This tank is a great performer for zooming around, but also as a distance fighter. with the 4.9s reload time, it can do a lot of damage. While not always, it does bounce some shots which gives a player an additional boost, especially in ending battle moments.