Bad idea: you want someone whose loyalty is not split but is only to you to look after your interests. The buyer's attorney cannot give you undivided loyalty, so you can't trust that he or she is going to vigorously defend your interests--the attorney may just be trying to close a deal and get paid, since he or she is not in an ethical position to aggressively advocate for or represent either side, on account of him or her having both sides as clients.