I used to hanker after a gear position indicator for my 750 ... and I got ribbed about it a few times when I mentioned it on the forum.
Like yourself though, I only really felt the need for a top gear indicator, to confirm that there weren't any left in the box and stop me searching for an extra gear (in my case, a sixth gear).
I can't see the point of an indicator for the lower gears ... its just a case of changing up or down as conditions dictate.
My bike has no revcounter and for the most part it doesn't need one but that does further complicate the issue when trying to decide whether there is another gear left in the box .. which there almost always isn't.
And as you say, dropping a tooth on the gearbox sprocket (which I did in order to create space for a crankcase saver, despite preferring my bike slightly overgeared) exaggerates the problem of the elusive extra gear.
In the end though, I stopped worrying about it .... and developed my skills at comparing road speed versus engine sound. This is much easier with a louder can though, as you can hardly hear the exhaust note at speed with the standard cans.
Its a fair excuse to be noisy, I guess. ......
