There’s multiple problems with pets for lock, and demo tree doesn’t really solve them.
Scaling isn’t even the biggest issue; resources are.
Everything will run out of mana mid fight. Succubus/felhunter will still melee, but will miss constantly because spell hit is not melee hit in classic. Imp will just have it’s DPS cut by 75% as it starts throwing a single fireball every 7s or so.
Taking damage talents from demo gives a very minor DPS increase by 60; taking resource talent gives them 15% mana, so maybe 20 more seconds of DPS.
Taking the CD/cast reduction talents from destro cuts their effective uptime in half, but will be edit, didn’t finish the sentence almost double the output while the mana lasts
Just as important as that life bar…SL only goes one way. If you’re demo using that (probably) felguard, every time you get hit so will the pet. Any boss with high raid damage will be nuking both you and the pet, resulting in significant downtime when it dies.
Sac isn’t even good for aff/destro…the way the tree is set up, you waste a massive number of points in things you absolutely won’t use (life/mana damage for the pet you’ll just kill, or faster summoning for your 30 minute buff). You’re 100% better off going shadow mastery/ruin for aff, or conflag/instant corruption+strong drain+tap, with imp damage for destro.
If demo is going to be a pve thing, it needs some serious rune work. SL returns HP to pet from lock healing and mana from lock lifetaps, and multisummons would be a good look. Right now demo is the “well, I have 3 extra points” tree.