I have all the crew skill at 400, so i basically pick scavenger and slicing plus another gather skill when i level new alts. Scavenger keep me refill on material, metal that allows me replace prototype armoring every 2 level and mod every 4 level.
If you can access HM operation it seem you can make money with all the crew skill. Cyrbertech for endgame armoring, mod, artifice for enhancement, hilt, color crystal and armtech craft barrels.
Armortech and Synthweaving wont' be useless since they are needed end game augments (willpower, strength, defense..etc for synthweaving and aim , cunning..etc for armortech.)
Armortech and Synthweaving can also craft pvp gear shell. (empty gear without any mod inside.)
I don't think pvp gear is going cut it for pve in terms of raiding since you gives up stats for expertise. But if you only focus on pvp crafting crew skill may not that important to you.
a lot of truth here.
dont forget armortech has it the easiest in making the augment kits. at endgame every new "shell" will need a new kit. this is for both pvp as well as pve. cartel appearance gear helps you here too.
i have all crew skills except armsmech which i dont need. i can get the barrels with coms for my alts. also they have the lesser used healer/dps augments for those who know what they are doing augment wise.
for alts now i too do scavenging and slicing but also archaeology so each toon can get their own mats while leveling
you can make credits with all crew skills . some are easier for you to "save" credits at endgame however. others are more useful while leveling certain classes.