Good idea for a topic!
I've done the racing thing, mostly 27 turn stock, and also enjoy a nice spot of bashing
My Charger/ discharger is the good old Pro-Trak. Fantastic piece of kit, when using the remote leads on non stick packs, you can monitor what each individual cell is doing during a charge/ discharge/ cycle. The good side of this is that if you have a few packs that are going soft, you can dismantle them, and build a good pack.
I think a good rule of thumb to work to is the higher the charge rate, the greater the punch from the cells, but shorter cell life due to heat. Both for Ni-Cads and NiMH.
When I was last racing, I was running GP3300 NiMH matched packs, and always found them best straight off the charger, charged at 5 sometimes 6 amps. Straight after the race they were discharged fully, and periodically equalised.
For bashing with old tamiya cars, you tend to be stuck with stick packs. I love the old Tamiya RC1400SP stick packs for this. Good punchy Ni-Cads which seem to suite silver can bashing well, especially with fully ball raced cars. Ni-Cads seem to respond well to pulse charging, where as NiMH seem to be better with a linear charge. again, I always make sure that they are fully discharged after each run. The only way I have come up with for equalising stick packs is to trickle charge them overnight, so that each cell has been fully charged, with no false peaking to worry about. trickle charging, which at best only gets the cells luke warm definately gives better run time, and longer pack life, but at the cost of performance.
I think my closing thoughts would be try not to leave any NiMH or Ni-Cad pack charged during storage, don't run the car until it stops, run until the performance noticeably slows, and if you want your cells to last a long time, avoid charging over 3.5 amps.
This is just my opinion chaps.