You are right: The metric option would have to be complete, from scorecards to all distances and elevations, including club lengths and scales. This looks like a lot but it's only automatic conversion.
PUHOLINO:P.S.: IMO, the only real problem with elevation in feet and inches on greens is that if it states 3 feet (not likely to happen though) it could infact only be 2 feet and 7 inches, thus making you overhit your putt by a lot.
This is a subject which we all share, nothing especially "metric".
Note aside: We would all profit from a metric display here :)
Our special problem is like this:
Imagine a putt from the front of green #17 of STA, maybe 80 ft long, 2 ft high. An unsuspecting "metric" player like me takes the numbers, 80 + 2, uses the rule of thumb and performs an 82 ft putt. Unfortunately it will stay 20 ft short. Even now, I have to think about it on every shot, while it's all automatic for others.