FES bike for complete quad 3 years post. Would it work?

I'm C5 complete 3 years post and and never tried a FES bike or any other kind of electrical stimulator on my legs. I'm considering in buying myself the device and use it in conjunction with my MotoMed. But now I'm worried that after the three years of not moving my leg muscles if they'll still be able to contract.
Any complete there that used a FES bike for the first time years after being injured?

FES bike for complete quad 3 years post. Would it work?