If you aren't sure what to buy, then it seems probably you may end up needing to do a type rating for what you finally get anyway, so you may as well learn in a small piston helicopter.
If you already have decided on a particular helicopter, however, you could always buy it first and learn in your own vehicle.
Personally, I'd suggest getting your PPL first, then you would have the freedom to find instructors/schools willing to give you a test flight where you can get the feel for the 120, 130, Gazelle, 206 etc. before making a decision.
One thing to keep in mind, the EC 120 and Gazelle both have a fenestron tail rotor. A standard tail rotor responds more linearly to pedal inputs, whereas a fenestron doesn't respond much to initial pedal input and then responds quite quickly.
Also the EC 120 (and I think the Gazelle) have the main rotor turning clockwise (European standard) rather than anti-clockwise (US standard) - you need to make the opposite pedal inputs (left pedal where you would use right etc.) when you move between the two.
This does mean if you learn in a R22 (anticlockwise, standard tail rotor) it may take you a little longer to get used to the pedals in a EC 120/130 (both in terms of which foot to use, and how much input to use), whereas if you learn in a Cabri G2 (clockwise, fenestron) it will be a little easier.
To be honest, moving between fenestron and tail rotors, and between US/EU main rotor direction feels a little strange at first but isn't that difficult (at worst, it may add an hour or two to the type rating training). Its mainly an issue for professionals who have to fly both on a regular basis, as it can be easy to temporarily forget which you are flying.
Matthew
Last edited by mdovey; 3rd Jan 2014 at 08:57.