Ours have never been spayed with a laser. They've "mostly" done fine, but the problems weren't due to the type of procedure.
Ellie had a stitch come loose (internal) and she had to be re-opened up 5 hrs later. We brought her home and when she got up to get a drink several hours later, she poured blood from the incision. But after that, she did great.
Mira's thyroid crashed after being spayed (really at the same time). She got rampant infections all over, PLUS since she has spondylosis (which we didn't know until then), she was in severe pain and was having difficulty walking. She was a very sick girl. After weeks of not having good success with traditional treatment, we took her to a holistic vet (who coordinates everything with our regular Vet), and within a week she was 90% better and was 100% in two.
Things CAN happen during a spay. However, they rarely do. There's always a risk with any surgical procedure, but if you don't get her spayed, there's also an increasing risk of pyo.
Ask the vet about the anesthesia, definitely ask about pain meds...and GET them, ask if the dog will stay overnight and if so is there someone there. If not...you might want to bring her home instead. And most of all...STAY with her for the first 24 hrs. Right in the same room. Leaving a dog who's had recent surgery alone is a risk. If we had decided that since Ellie seemed fine and was sleeping, that it was okay for us to go out to eat or something....she may not have lived. She was bleeding profusely. And as I said, that was hours after we brought her home.
So just do your research, talk to the Vet, and I'm sure she'll be just fine!