i have had a mechanical oil gauge in my car for almost 3 years now, and have not had one problem, nor have i had one leak. I beleive that the mechanical is quicker responding than the electical, but gauges have come a long way and the electrical gauges are getttin better and better. Its all gonna come down to personal opinion. some people like mechanical, and others like electrical. some people have had problems with mechanical, and others with electrical. as long as u run the line for the mechanical oil pressure gauge good, and have the line go thorugh a rubber grommet, i dont think that there will be any problem! just my 2 cents!
craig