The primary advantage to the 850, 800, and 650 is that they are capable of emitting both IR (infrared) and RF (radio frequency) signals, while the 700 is IR only. You can read about the advantages RF can provide
here.
The RF capability is, I believe, the only difference between the 700 and 800. These are both recently discontinued models and can be found online for very nice prices. If you want or need RF capability, I’d stick to the 650 or 850. So far, the big difference between the 650 and 850 that I've been able to determine, is that the 850 uses the computer software for programming. If so, I'd eliminate the 650. I LOVE being able to program my MX-700 on the computer.
That would narrow it down to the MX-700 or MX-850. If you want, or need, RF capability then the 850 is the one for you at $499.00.
The new models, the 650 and the 850, have a redesigned "Select" button in the center of the joystick that should be a slight improvement over the same button in the 700. I think the new models also have “new laser etched buttons.”
More info on all these models can be found
here.
Being discontinued, I don’t think you can find an MX-700 with the accompanying MX-200 sidekick anymore. They stopped making the sidekick some time ago, and I’ve not been able to find one anywhere. So, if you go the MX-700 route, be sure to pick up an open box model, for around $180 at either
SurfRemoteControl, or at
BlueDo. Both are authorized dealers, so the remote will be completely warranted.
If you want the RF capability, and/or the new “Select” button, and/or laser etched buttons, then the 850 is the considerably more expensive thing for you at $499.00. You can get the 850 without the MRF250 Base Station for $399.00, but you lose the RF capability without the Base Station. The 850 is available at both the above web sites, or you can look for it on EBay for considerably less money, but no warranty. To further complicate the 850 I’ve seen it called the “Orion,” and I’ve seen it called the “Aeros.” I have no idea what that’s all about.
Good luck, and holler if you have more questions.
