I've been flying a Slow-G (Twin-Rotor SlowStick) for a couple years now. I had the exact same problem at first. The prop wash is making it more difficult for the right rotor to spin up. Here's what I do:

1. If you're outside, make sure you're pointed into the wind;
2. Pre-spin the right rotor by hand (leave the left one alone);
3. Take-off quickly while the right rotor is spinning.

You may still have to make slight corrections when you lift off, but it works great for me. I've even flown my off water!