The Pro2 have been discontinued for around 2 years. Are you able to get a new one?
For bashing and fun, I would say the Sport2. It's cheaper, a little easier to setup (due to more flex) and it requires less maintenance.
For racing, the Pro2 is best. Better handling due to saddle pack. Way better shocks and CVD's instead of dog bones. Ball diffs. Turnbuckles. Graphite chassis.
If you are not sure, an option could be to start with the Sport2 and later get the saddle pack option. Maybe a one-way. In this configuration, I beat many cars, which are considered better/pro.
But if you get more serious later, you'll be better of with the Pro2. I've just purchased a brand new Pro2. It's nice.
Schumacher Mi5 - Sanwa MT-4 / RX-462 / KO Propo PDS-2123 - Nosram 5600 X-treme Saddle Pack - LRP SPX Zero/X12 17,5 - Nosram Stealth Touch Evolution - MAAS SPS 9250