With an early-stage company, i.e one having not yet raised its Series B, a high-value employee should be able to negotiate almost everything. The earlier-stage and higher-valued the employee, the likelier the company is to budge.

I wouldn't encourage anyone to turn down an offer for its lack of cashless exercisability. The lack thereof, however, causes pain. That should be compensated for. On transferability, I would mark down non-transferable stock to zero in any salary-or-equity trade-off calculation.