RE: first time pilot buying engine- will it last long enough to warrant buying one with bearings?
Either of those engines will easily run for about 10 years, if not destroyed in a crash. The bushing engine doesn't develop as much power. Bushing engines generally have less sophisticated carbs with less fine tuning. Ball Bearing engines turn more RPM,s develop more horse power and have better carbs with a high a low speed fine needle adjustment.
Bushng engines are shorter. They weigh less. They are slightly less reliable because you can't tune them as well.
My advise: Don't cut corners on the engine. A good running and reliable engine is key to an enjoyable experience.