Re: Prior art
Yup, LSBUD is something that anyone digging holes should be consulting, Sadly, lots of people don't.
However, as you note, not every sub-surface utility is accurately mapped, and if the records are wrong/incomplete, then however comprehensive your record search, you could still hit something (or not find what you are looking for - you might be trying to actually locate the service, rather than miss it, of course).
So the value of this new digital mapping may depend on whether they are simply transferring exiting records into a new database/accessible mapping tool, or will actually do anything to confirm/verify/correct the data.
There is something called PAS128 (not a British Standard, but produced by BSi as the nearest thing to a standard) which is the standard for locating underground services, and that sets down 4 different types of survey / level of confidence, depending on what you need. The highest category (A) involves positive-identification of location (broadly, you dig a hole and positively find things).
GPR survey is Cat B.
PAS128 is about 7 years old now, so we've been trying to get this right for sometime.