I've given serious consideration to going down that route in a couple of years time, but the figures I've heard bandied about for cost are staggering. Upwards of $40,000USD was one rumour, and if you price the 914 at a little over $30,000USD that sounds somewhat consistent.
IT would be the perfect match for a -9 if you could get it to balance, and I've no doubt it would be doable, but is the weight saving & performance worth the cost?
Time will tell.