I've finally started to use this Aerogramme pad and I'd say that it was probably made for ball pens rather fountain pen.
The writing part of the paper is white but has a smooth feel to it, almost like glossy printer paper. That's probably already a bad sign.
I've used Hermès' Rouge H ink in this test (don't tell them it's in a Pilot Kakuno! Medium nib by the way) and it feathers a fair bit. Not disastrously so, but noticeable. I've attached a photo of the other side of the paper, clearly showing ink seeping to the other side.
I usually use an Avery label for the address, so it is still mail-able.
The entire pad is quality though. To the texture of the cover, the way the paper detaches from the pad, etc. So it should, for 35+€. Too bad it is not 100% fountain pen friendly.