It is not much fun dealing with anesthesia.
I can't help you with the size thing because Ellie is 5 1/2 pounds. If she has done well for the last two, you must have a good vet.
Do you brush her teeth daily or use something on them? You might be able to get out of dentals altogether if this works out.
What you were quoted is entirely too much for a dental. I wouldn't be too happy with that. I believe vets deserve a lot of money but a little teeth cleaning can't take more than 20 or 25 minutes. Ellie's vet is very expensive and it cost me just about $600 for a teeth cleaning, getting 9 adult teeth pulled, cleaning under the gums (I think), oravet home care kit, oravet first application, pain med, anesthesia, xrays and preop bloodwork. I wonder why a simple cleaning is $700. If Ellie's vet charged that much I would pay it because I like her so much and trust her, but that is really over double the highest it should be.