Boyd's a great squad player for the simple fact that he WILL get goals. Given his goal scoring record I wouldn't let him leave for anything less than £5m. If he was going to the premiership, double it.
Coisty was criticised for all the same reasons Boyd is and it took the arrival of Mark Hateley to develop his play outside the box. Maybe if Boyd had a suitable partner (and we started playing 2 up again) we might see some development in Boyd.