well 7,500 miles on my Kodiak doing the measure only trick and 5,000 miles on my Grizz doing it that way and zero troubles with either of my diffs.
your putting in the amount the manual calls for.....just not filling it to the hole.
How many miles do you have on yours honda buster?

 

A little under 2000, but its done it since new, and the dealer told me to fill it to the top of the hole.
I used to think it was too full,and that caused the pumping out, but if i drove it for an hour or so, and checked it, it would be way down. Then id drain it to see how much was in there, and itd be almost empty (about 2 tablespoons or one ounce). It just didnt seem like enough for me. Id sure hate to have rear gear troubles because i didnt have enough in it. I tried getting the dealer to look at it before the warentee was over, and he said its normal, for it to burp out fluid, but to just keep topping it off. That was too much hassle to carry a bottle of gear oil, so the bellows seemed like the best solution. Now it doesnt use a drop, its always at the top of the hole.