I think it depends on other factors and which side you want to favor in the various trade-offs..

First, i think it depends heavily on what the program does -- is it something (e.g. number crunching) where you should be using c++ (or whatever) for speed anyways? Is it something that perl can do very well/your personal development time will be very much less using perl (e.g. string manipulation, or heavy leverage of CPAN modules, etc)?

Next, what does the user want? What is the user base (is it a client? tech level?)? If they will find it unacceptable, that makes the decision there for you.. but OTOH they might like the rapid development time and be more than willing to have it look a little "funny" just to get it fast .. or they may not even know enough to know the difference..