keithl... I couldn't agree with you more about your "note of caution". Despite being a procedure designer, I'm also a practicing pilot (and, man, do I ever need the practice!
) But, seriously, I like to have my level segment and our SOPs allow it.
FWW... Yes the noise and fuel burn issues are important considerations. They are going to be your best debate points with the Fleet Captain - especially the latter because every extra pound of fuel burned is an added cost on the operation. And this is normally at quite a low level, so the extra fuel burn could be considerable. Yiu may, however, need to develop some figures on that, to place before the Fleet Captain, so that he can see how much extra money it'll cost the airline over a year.
The only thing that I would draw to your attention is that the worst aspect of a "false GP" is that it provides premature descent below the actual GP. The amount of deviation below the real GP can easily exceed the protection that is provided to ILS procedures. I've done some research on this and it seems that rate of descent is likely to be excessive, though this isn't always going to be a good clue.
Personally, I like to use DME to check against my altitude. In my part of the world, ILS approach charts include a DME Dist Vs Altitude table, which makes the GP monitoring very easy. And, yes, because I've designed the approach, I've already worked out the DME Dist Vs Altitude table.