It's true, clinically, MFTs and PsyDs do virtually the same work. A big difference is that insurance companies reimburse PsyDs (and PhDs for that matter) at a higher rate. Granted, since most PsyDs are not funded during their time at school... the difference in the long term is pretty minimal. Besides for reimbursement, PsyDs are usually more sought after candidates for administrative positions at mental health agencys and still have an opportunity to teach (although most predomintely at for-profit professional schools, i.e. Adler).
I think it's all a question of what you want to do, PJones. Overall, I would agree with Darwin. If clinical work is your main goal, skip the PsyD and build your career around your MFT.