Just had a really good pug on mainline. My thoughts are a bit scattered and I don't have much to offer, but the small health pack on the weird badlands style displacement in the left (long) path to middle needs to be reworked. Its really annoying trying to get that pack and as a medic running back to resupply I could see myself getting stuck for just .5 seconds and getting reamed by any spam.
I guess that left path seems to be the very dominant section of the map. The interior space between mid and 2nd is really hard to navigate and you get the hell spammed out of you trying to get out of it. The left path is longer, but it offers such a spam free avenue for approach, plus a bit of height, that I see teams using it almos exclusively to get to second. Just what I noticed anyway.
Last seems fun. The stairs are pretty fun to dance around on. However, I would watch the ledge below the point. Seems a pretty annoying place to get hung up on. Especially when combat gets so crazy.