There was a huge thread on the 5-speed some time ago, try the Archives.
Bottom line was forever on backorder, and operational issues.
Brilliant concept, but an experience I wouldn't pay $3,500 for, let alone $7,000...
If I already had a 4-speed, I would not fork up an additional $3500 for an OD, but since I do not currently have a trans and need one anyway, the difference is not that big once you consider buying a 4-speed trans and having it gone through, etc...
Just my .02c
but, yea, it's a lot of $$$