I picked up a used Concept2 Model D (with PM5) just before Christmas. I agree you need to be careful with form, but it isn't that hard. I like the machine and feel it is helping. Honestly, I need to pay more attention to stroke rate to make use of the C2 daily workouts and suggestions from DarkHorse. But, just putting in some time every day isn't too difficult. I would suggest picking one up. In my area they hold their (used) resale value well so you can always unload it if you don't take to it.
Don't be intimidated by the damper setting. It works different from other cardio machines. There are good videos that can explain it better than I can. But, basically - higher isn't necessarily harder.
One note - I haven't figured out the best aerobic zone. Apparently the target zone for a rower is different from running (or biking) so you might have to play with that a bit to dial it in for optimal effectiveness.
Don't be intimidated by the damper setting. It works different from other cardio machines. There are good videos that can explain it better than I can. But, basically - higher isn't necessarily harder.
One note - I haven't figured out the best aerobic zone. Apparently the target zone for a rower is different from running (or biking) so you might have to play with that a bit to dial it in for optimal effectiveness.