G_Brill, your 750mah battery will most likely charge OK with your radio's wall wart charger. A 750 mah batt will most likely provide you 60 to 70 minutes of actual in flight time, with some reserve left. using 4 STANDARD servos. High torque output servos or DIGITAL, nay-not so. Back in the '70s and '80s anything over 800 mah output was some kind of high expense item not available to the average RCer. We flew and flew. I still use them in my smaller models.

I have been performing some tests, and the average wall-wart charger with 50 to 75 mah output will NOT fully charge a 2000 mah Nimh or Nicad battery. In fact a fully charged 1500 sub-c Nicad batt. will not maintain a full charge when fully powered with a 50 mah wall-wart charger being used as a trickle charger. I have not experimented with large Nimh. However my transmitters are all equipped with 1500 to 2000 mah Nimh and they will loose the top end rather quickly, but maintain stated voltage longer.

Radio Shack stores have fantastic discounts every so often as they change out stocked items. A couple weeks ago I purchased two 800 mah 4 AAA cell packs for 2.97 each. I bought several 2 cell packs of1500 mah AA Nimh for 2.97 each. They have cycled beautifully after 3 runs. All I have to do is make a clip or two, solder on a proper connector and good to go. I have plenty connectors from old packs that seem to not do well anymore.
In addition I have purchased some excellent chargers with plane and transmitter capability at RS for as little as 47 CENTS each, but usually at 3 to 5 $$$. Need some tad of outside connector rewiring and good to go. Several are good for all ranges of voltage from 1.5 to 12 V. with a 300 to 500 mah output.

All these bargains are somewhat like a woman buying shoes. I have far too much electric equipment.