I wanting to purchase my first 4 cycle engine for my Big Stik which is for 60 size, 2 cycle engines. I'm new to RC started last year been flying without an instructor for about two months. I'm looking for an easy to run, easy to maintain engine. I would like to know you opinion on the O.S FX-70 II Surpass and the O.S. FS-91 II Surpass. Weight difference is 2.35 oz. Give me both pros and cons. If you have any views on the Saito 72 pass them along.