Valdac has a small place in certain bgs, and it's not so much that he is "trash" it's just it's hard to justify him in this horrible meta.
It's not an overly nuanced BG to play. Keep deploying to retain hunter:walker, engage when they can't easily 1 round your stuff (which is quite often given SL bonus, def values and hunter) - back up your melee with imperator and whorl.
What would you guys say is SL meta weak against? I really can't think of anything. But that would be the thing to play now-a-days.
Nothing really, however FS psychic does have a decent matchup in my experience since you can nuke their void shields with a single spell and your insane damage on top of sabotage psychic makes the SL bonus less effective relatively. Not to mention the rest of the FS package is nutty in general and 2x firk infiltrator changes the dynamics of every game in your favour vs factions that don't run 2x global detections/pings (only 1x snogvie).
Skeezick whorl is a real pain in the ass in sl, ad watching sl retreat and re-heal while they take such little damage already is very annoying. Unless i'm playing fw versus sl I usually just quit.