They are very close at 59 on live, incendiary did 1183 and frost did 1052 with 5.6 vers... not that similar at low levels. At 23 (or 4) incendiary hit for 451 and frost for 401 with 3.5% vers. Seems weird, so i'll double check, but not scaling down the same.
I can check the PTR in a bit, but i'd wager the outcome to be similar. I'll let you know.
edit- at 59 on the PTR incendiary hit for 864 and frost hit for 767. Same toon as above.
at 24 on the PTR incendiary hit for 304 and frost hit for 272, again same toon as above.
I should note that a +13 scope scales down to +4 at 24 and added about 20% damage to aimed and arcane shots. So for that level 24, it was +60 damage every single non-crit aimed shot and around +20 to every arcane. Reliable increase.
Fishing for procs is sometimes not worth it, IMO. Especially when they are going down...
So +damage scopes seem untouched so far.
edited again, scope was the +13
https://www.wowhead.com/item=44739/diamond-cut-refractor-scope, it's "+10" to all my 59 making it. Sorry.
https://www.wowhead.com/spell=30332/khorium-scope says it's also +4 at 24, but it hits for a little less than
https://www.wowhead.com/item=44739/diamond-cut-refractor-scope which shows the same. Less at 59 too, even tho it says +11 compared to the diamond that says +10 on the weapon itself when applied.