It just looks kinda wrong to me - If your generic template has to switch on what type it's been passed, surely you've made it too generic somewhere? Adding back conditional compilation or execution afterwards strikes me as the same sort of code-smell as checking if something is an instance of a given class before then casting it and calling a member - you've lost information and using some sort of reflection to get it back looks like poorly thought out code. Sure, there are times when you more or less have to, but you ought to try to avoid them.

But what do I know, I haven't done C++ for about 5 years and was never that into it.