Preface: I am not pro and will never be. I'll just give you some of my thoughts, in case you or anyone else is interested.
My current uses for Troops are these: to unlock skimmers and survive long enough to nab objectives. The other use, as part of an alpha strike Raider Rush strategy, doesn't fit my playstyle. I have run into too many walls of fire and superior enemy CC troops too many times, so a methodical, shootier strategy is my current goal. To that end, I actually took 5 man Wych squads for all of my Troops, as they 1) Unlock skimmers cheaply and 2) Can get Feel No Pain to survive and 3) Can tie up enemy shooty units and Haywire. In practice, when my skimmers blow, the Wyches blow as well, even if my whole army is sitting back in my deployment zone. Or, when they go in to Haywire, they are exposed and also tend to blow up. Very few ladies survive to claim objectives, which is necessary as I won't be tabling anyone (see: Preface).
So, I suspect Warriors are a good choice to alleviate these woes. Additionally, leaving the unit out of its dedicated transport when appropriate preserves some fragile space elves from collateral damage. I just need to be pinging my opponent with a few more splinter shots or an extra Lance or two, and Warriors do both of these things while standing a respectable distance from the enemy, Only a 10-man squad will outdamage their attached skimmer, and only at Rapid Fire range, but the possibility is there. Wyches will probably stay in case of parking lot, where there inevtable deaths will save many more lives. And that's the main thing: having each unit contribute as much as they can.
As for Wracks, I don't have much experience. The necessity to get close, coupled with their inability to threaten AV11+, makes me skeptical. I have only used them to escort an IC. 3-man squads definitely win in both the Cheap Skimmer Unlock and Survive categories, as they can camp out on a home base while their Venom goes to work. Warriors get to shoot at anything that gets close to their house, though, starting at 24", which is a big difference from Template range.