As a potential seller the sticking point would be the reserve price. I wouldn't allow myself to be 'exposed' by Sedo's valuation methodology. If the price isn't 'right' I'm not placing and I'm not selling, full stop.
I've had Sedo very obviously trying to put the squeeze on before during brokered negotiations with talk of absolute deadlines et.c.,and I've called their bluff and the 'absolute' has then suddenly become 'relative'. My asset, my terms. No intermediary is going to short change me. Sedo has nothing more than first mover advantage and accrued good will, and that crucial second aspect is being eroded day by day.