Personally, I don't think it's a good idea to write a launcher as a second blitz exe. Simply because a biltz exe is so large.
With UPX it is something like 500K? That's smaller than most of my texturemaps and models - and there will be DOZENS of them! So 500K is nothing. Exe size might be an issue for ppl who want to have very small game that is easily downloadable and can be put on a 1.44MB floppy disk - but my goals are different. My game will be in the end so big project that it will be close to commercial game demos (>100 MB). As you can see 500K really is nothing... :)
A launcher made in something like PB would make a lot more sense.
What does not make sense is me buying Blitz+ too just for shaving few KBs...?
But really, how much extra memory do you figure you're saving, anyway?
I do not care about the memory usage at all... what I want is easy "housekeeping", ie getting rid of all the stuff that is not need for actual gameplay (and might mess up my game code and be hard to debug). Also keeping them separate projects is better (easier) in coding wise... I can develop "launcher.exe" more easily because it's smaller and does not have any game stuff code in it.
...But everybody is free to do their stuff just like they want, but this is the right way for me and my game. Most commercial games use separate launchers too.