I would say those who are soooooooo sceptical about lipos have not used them. Not saying its 100% safe but they do not always blow. You have a higher risk of getting killed driving to the post office than flying a 100S set up flying at a million miles.

If you want speed the main issue is NOT your power set up. Even a brick can reach 800 mph if you tie it to a rocket. Your fuse is the main hurdle. So you want to go fast ... with what sort of plane? Aerobatic plane? Scale plane? Hotliner? Flying wing? You need to decide on that 1st. Also, how big a plane do you want?

My Micro Jet is doing 80 mph on a simple set up. I had a little pylon racing plane that was faster than then MJ with an even cheaper set up. So you need to decide on what plane first. Something like the P51 will need more power to get to 85 mph than a hotliner. But again, the P51 looks sharp.