Math? If you have 8 free slots from items/wep and difference between +24 and +22 is 2? Thinking.You must decide whether +30 more mainstats or +200 armor is worth the farming.
So a 175 purple fragment can not crit to a +24/180 talisman. You need to have a 200/200/200/200 (purple) who critts to get a +24/180. If a +22 crits it gets to +23.Well getting 200 purple fragments of salvaging is not currently possible. Where is no 40+ purple gear out there.
Worry not, latest changes makes getting them of scavenging almost impossible also, because you will have to spend time equal of getting full conq to get a somewhat decent amount of fragments.
And no, it's not 200 armor, so you don't have to "decide" anything. 200 purple fragment with 175 essence and rest 200 mats gives you +150 armor tali and crits for +180. I've heard you get 200 essence salvaging Anni helm, but don't have a spare one to test. I'm pretty sure (according to crafting add-on) that +180 crit is maximum you can get anyways (armor I mean).
For rest stats it's +22 and +24 crit. Something like 89-120 for resists, I'm not sure
Here is info on how Talismans works: http://warhammerfantasy.wikia.com/wiki/ ... man_Making