HI
Currently I have one plane with Pletteberg 30-10 Evo and one with Hacker C50 14-XL. With slightly different propeller-size, the flight performance is very similar. I can not explain why, but the Hacker equiped plane uses 10-15% less capacity from the battery per flight. If you have to pay full price for all the equipment, the cost of the motor/regulator is insignificant over time. Your main cost is related to the batteries. This is the same as with glow-engines and fuel. Since the Hacker solution presents a lighter load to the batteries, the batteries will probably last longer ....
The downside with a geared inrunner is some rather easy and fast maintenace (greasing of bearings in the gearbox) every 100 flights or so.