Thanks for your kind words it is nice to be appreciated I really enjoyed my time at BFC. Regarding where such pitches can be seen locally you do not have to go far there are several in London area,
Emirates, Spurs, Qpr, Reading, Watford, West ham.
In my opinion the best example of a ground share is at Swansea city where they have done a tremendous job on a limited budget.
There are two schools of thought on which rugby code does most damage, whilst rugby league is even less damaging than football it is played throughout summer which severely restricts the renovation window thus the pitch then suffers in the winter. Union is the most damaging second only to american football but follows roughly the same season as the football so allows a good window of opportunity for renovation which is critical on an annual basis. Still like i said it is possible for BFC to have the first team, a rugby code and keep the chelsea reserves, plus the fa youth team games and have realistically 1 large concert per year and have an excellent surface, plus several community events and most important of all the fans game!
I stress 'possible' but of course the right technology design and construction, maintenance and equipment need to be in place for the end result to be satisfactory. Since the multi use aspect appears to be a strong part of the legacy of your new stadium then the playing surface should be a high priority with the powers that be and the alloted budget for that area should reflect that. A new stadium is the ideal time to put it all in place and its very difficult to correct things later as time frames won't allow it.