Safety: depends on the mechanic. Some are very lenient, some not so much. The grey area for me is the integrated tails. If there is a separate "bulb" for the signals (ie isn't half the brake light flashing a different colour), no problem as long as they can be seen. Just make sure they flash, you have a plate light and your brake switches work.
Cop: depends on the cop and rider combination. If you go by him/her on the rear wheel or are acting stupid in traffic, they are going to find everything that might be worng with the bike and through the book at you. Otherwise, they really have other things more important than hassling you for your lights.