What pack are you currently using?
I haven't used those packs, specifically, but have used a few in the 36- to 50-liter range and find that what fits into a 38-liter Zpacks Zero will also fit into a 36-liter GG Murmur and 38-liter Waymark Evlv. Ditto for my old-style (2011) Arc Blast 52-liter and Arc Air 50-liter.
I do have a MLD Core (28 liter) and it is well made. I added a mesh pocket to the front, however, because I find that such a damn handy feature that I simply can't live without it. I use the shoulder strap pockets for 20-oz Gatorade bottles and it works out very well. I also added some little shock cord triangles, a la Zpacks Zero, to hold a sit pad on the back.
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