Keep and fix the RS shell, Put the Bonus roof on it if needed. Money shouldn't be an object to anyone who is an RS owner. If you don't like that these cars need money throwing it at on a regular basis, RS ownership is not for you(Not you in person, Just a saying).
However there's nothing wrong with re-shelling them as long as you don't call it an RS or badge it up as an RS.
The more that get re-shelled means that the genuine ones will rise in price, so that's a bonus for me and others.