I have a highly costumized CAP 232 in my RealFlight G2 which I use for training. The model is based on the downloaded, from realflights homepage G2 swap page, model "2 meter CAP232" and it comes with a very good engine but rediculous aileron throws and way to much elevator. The rest is setup so it feels right, i.e servo speed, control throws, exp rate, balance, weight of wingpanels and so on ...Very exhaustive to do....I have recently purchased the G3 and there is somebody who has made a Pinnacle and even a Genesis you can download from the G3 swap page and they are very nice looking planes, but they feel totally unrealistic to fly or manouver around. All parameters have to be adjusted to give the same response and power feeling youd get flying the real thing. I'm keeping my G2 for this reason.
I have not flown other simulators, just on very rare occasions, so I only speak for the realflight and I would say yes, you can use this simulator for training. You'd have to learn to count the time in your head for which the plane "are flying in the sky" , because you loose ground view and you will miss placing the manouver correctly. This will take some time to learn. ( But then again: Mike Hailwood counted his way through the turns on Isle of Man because it was foggy, doing a 100 mph on his Ducati ).