I've got Etys and a SuperMini. IMHO, they were MADE for each other, especially while flying.
This amp is almost unnoticable when traveling. Heck, a decent interconnect weighs as much or more than the amp! It's literally JUST over the size and weight of 4 AAA batteries. You can attach it to your CDP or MD (or whatever) using some Velcro so that it stays put.
Battery life is incredible... I've gone for well over 100 hours before needing to change batteries. Which, if you're really worried about weight, means that you don't have to lug around extra batteries while you're on a trip.
OK, it's teeny-tiny. But how does it sound?
Excellent! Although I don't have a META42 to directly compare, others that do have reported that the META is superior sounding... but that they are very close. Do a search on META and Fixup and you'll find the comparissons.
If you are concerned about uberportability AND sound quality, Fixup SuperMini is a terrific product.
Good luck!
Bruce