I'm in the market and I see these helis being very similar. I asked a question earlier today about the main differences in the two. Below is the answer. The other difference is the LHS support for the mSR. Nine Eagles has part sellers in the US, but I can't just go do the road to get parts like I can with the mSR.
Which do you think is the better choice?
Originally Posted by eriskio
The main difference:
The Solo PRO is a project based on the Bell flybar (without paddles) while MSR is a Hiller design (with paddles on flybar). Both of them have a 45° design, but this is a way to have some kind of swash MIX without the complex linkage of bigger helis.
The Solo Pro main rotor is self-stabilizing on a HORIZONTAL PLANE. If you give left stick the heli will probably start to go here and there, but always horizontal.
The mSR being based on Hiller flybar (with paddles and - theoretically - no mass) is auto-stabilizing the rotor in a different way: it will force the rotor to STAY ON THE PLANE THAT YOU IMPOSE throught stick movements. That means, you can try to put the rotor on a plane perpendicular to the ground (well, unfeasible as a static position, but it may be possible inside fast, dynamic manuevers).
The visible effect is that, for example, if you want to make the heli move forward:
1) on the Solo PRO you have to keep your TX stick pushed forward always at the given "level" whenever you want the heli to move forward with a given speed.
2) on the MSR you have to push your TX stick just a bit releasing it as fast as the heli starts moving forward, continuosly adjusting your input to keep the speed and direction you desire.
The main difference is that MSR can do more complex manuevers and offers better performance (speed at first) while the Solo Pro is more relaxing and fun to fly (maybe in the evening after a day of hard work).