No, their conflict as a romantic couple has little to do with the their disability.  It has all to do with their social status (he coming from money/she from a poor family).  This play is so comically alive because that text-to-speech device is perfect for dead pan humor.  Put any joke in it and the laugh works.  I loved the relationship between the two central characters.  I loved how they struggled BEYOND their disability and were never limited by their difference.  If anything, their speech limitation made them slow down and be more deliberate in what they were saying and hence their communication was richer and alive. It was obviously so smart to cast two actors that live and work with the challenge of a life in a wheelchair – but, as I understand it do not have the speech challenge the play dramatizes. They are “faking” that part and it really does show. They hit only a few buttons on their speech device and whole clever sentences come out. To me, it did detract from the realism of the rest of the play.