I own the follwing:
MX500 - corded
MX700 - wireless
MX1000 - wireless
MS Optical 3.0 - wireless
The MX1000 handsdown is #1 in my book....good feel and solid. Only had it 2 weeks, haven't recharged it yet. The MX1000 uses FastRF which means its throughput is at USB speed...MX700 uses this also I believe. Internal Li-Ion battery, cradle charger.
MX700 is good for gaming, but I do have a rare jitter problem when working in non-game apps....but in games it never bothered me. Battery lasts about 4 days of 8-5 office use....two AA nimh batts...cradle charger.
MX500 - same performance as the MX700 but is lighter....but I cannot stand the cord anymore....
MS Optical - POS....major lag issue, forget being a sniper with this slug, alkanline batts last 4-6 months. I use it when setting up systems and presentations. I've used 2 of these units....
My $.02