I've owned a PIK20E for about 350 hrs of flying. The engine definitely changes the way you fly and think. The biggest advantage (when good landing fields are available) I would move on for better lift when moderately low, in the motor glider. In pure gliders, I will usually accept weak lift when below my working band of altitude, so possibly wasting lot's time when a good lift is ahead on course. Of course the MG climbs worse or not at all in weak lift, where as the Libelle I fly now will climb in very weak lift. I used the motor many time for avoiding landing out. Yes, you better give up at a higher altitude with a MG, the motor got me into a few dicey situations I now know were risky, and looking at the traces of MG flights on OLC of pilots some take serious risks getting low. You better expect the motor to fail at any time! The PIK was a complex airplane to fly lot's of ways to screw up (I think I found a lot of them), a lot more to worry about. I learned a huge amount about flying XC in the MG that I wouldn't in pure gliders.. Mainly stay on course when getting low, don't dart all around desperately looking for lift, move on from lift when it gets weak. I was able to launch earlier and fly later in the day, knowing if the lift isn't there the motor will probably prevent a landout. So, yes both have advantages and disadvantages. As far as being in the same category for record flights, no way the motor really changes the equation.