I personally wouldnt bother with sanding the slots at all and let the pack "ride high" as you put it. The lipo weighs less than a NiMH pack so its not likely to affect centre of gravity even when sitting higher. THe TA05 has a nicely protected area for the battery so I wouldnt let that concern you either.
That being said, chances are the larger than 3800 capacity packs will be taller so other brands may also suffer this issue. Incidentally, the Intellect IP3800 fits nicely in my TA05 but its one of the shorter packs.
-Mark