The standard 4 channel transmitter is able to operate over 2.5 hrs on a good 500 mah battery. The limiting factor of how long its safe to fly is almost always the receiver battery. My old (power hungry compared to the new computer radios) Futaba computer radio uses 360 mah/hr of operation. (so the computer radios will safely go beyond 1.5 hrs on the common 600 mah packs that come with them.)

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Noise is going to be the main reason that electric is eventually going to drive glow power out. Quiet flight will get rid of the noise complants that have closed a lot of model airfields over the years.

In the long run, (If you stick with flying, and you do a lot of flying) electric will end up cheaper, even if you get the expensive brushless gear drive systems. That $12 to $30 a gallon for glow fuel adds up.

I expect electric power costs to drop considerably in the next 3 to 5 years. There isn't enough manufacturing cost difference in the ESC's for brushless to justify them costing 3 times what a "standard"ESC costs... its just that they are the nwe super product and the manufacturers need to recover development costs still. Some of the planetary gear drives are already starting to come down... some of the brushless motors are already starting to come down. The more peoiple that buy this stuff, the cheaper its going to get.

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Right now... its gotten to where its not prohibitively expnsive to go electric on a .40 size trainer using brushless equipment. Appx 1 year's worth of flying would save the cost difference vs starting out glow powered if you carefully pick your equipment. (Polk's Hobbies has the lowest cost good quality planetary gear drives I have seen... 30% to 50% of the cost of some equivilent gear systems)