I couldnt imagine flying anything at all without practicing on a sim for many hours first. Trainers fly the same way any other plane does,so to me,that wouldnt have helped either. Sims teach you orientation......And thats by FAR the hardest,most important,and potentially the most expensive part of learning to fly. Once you get that down,the rest is trivial.
Sure,you could still learn with an instructor,but it would be 10 times as frustraiting not just for you,but for your instructor.....plus it would take ten times as long because you wouldnt have the benifit of just crashing over and over again to learn from. And thats how you learn!!!
You wouldnt even need the newest and best sim like a G4. Yeah,it would be nice...but not needed. I learned using a free sim I downloaded of the internet (FMS flight sim) that I was able to configure to a gaming joystick I had laying around that worked in the same manner as an R/C controller. If I did want to buy a sim,I would probably just buy an old used version like G2 or G3....if that off ebay for much cheaper than a new one.
Whatever you decide..........GET A SIM!!! It'll be the best investment you could make in learning to fly R/C by FAR.
[8D]