Got the custom sleeves for my Etymotic HF3 the other day.
First, all-in, they were only $81, not the quoted $100.
I haven't been on a trip yet, but have been wearing them a bit to get some practice putting them in. The noise isolation seems to be about the same or slightly better than the triple flange I was using before. Sound quality is a bit better, the bass seems both better balanced and deeper. Very comfortable, and VERY secure - once they are in, they don't move around or slip out.
Money well spent IMHO