Good intermediate helicopter?

I would upgrade to a 4 channel just because it's the next step from the 3 channel you are flying now. If you think your 3 channel is boring and you are flying and landing regularly without incident, then you probably could move up to the 6 channel. I started off learning with a 6 channel, never flew a heli before, and it took me a while to learn and get the hang of it. I should have started with a 4 channel. But since you have experience, maybe a 6 channel would be better for you. I would suggest www.xheli.com for your next purchase. They are quality helis and very affordable. I have been dealing with them for years and they have always been good to me. Parts are always in stock and have a full line of upgrade and custom parts. Hope this helps!