The Fixed Pitch MSR is not a realistic trainer for a Collective Pitch helicopter, which is why I did not rate the MSR "Highly Recommended." The SR is more difficult to hover and fly than an MSR, and it is much easier to damage (first timers will benefit from training gear), so it demands more care. While some think the MSR is tricky to fly, it is actually too stable to provide a useful lead-into a larger CP heli. In RTF form, the SR only costs about $40 more than an MSR and it comes with a real heli radio and the same adjustable gyro as the Blade 400, making it a better deal. And unlike the MSR, the SR develops a relevant Collective Pitch skill set and is a genuine stepping stone to larger CP helicopters. The MSR is fun to learn, but it flies in a too-easy, single rotor Fixed Pitch skills niche, mostly by itself.
For the more daring and possibly more wealthy, it is ok to go from an MCX or CX to a Blade 400. The 400 is a hotter flier than the SR, but when tamed with low response rates, it can be a more docile flier than an SR and without the tail twitch. It's larger scale is a little more forgiving of wind. Without a lot of simulator time and someone to set up your low rates (buying the RTF version then dialing down the preset DX6i rates to 50% is also fine), you'll probably crash either the SR or the 400 in a jump from coaxial, so the daring + dumb should stick to an SR.