what are the advantages and disadvantages to this?
utilizes more muscle fibers and allows for more movement than with a standard barbell bench, people usually say dumbell bench for mass and barbell for strength, u should switch between the two every so often...
You can gain size by doing dumbbells. I broke through a plateau and actually achieved muscle hypertrophy from doing dumbbell bench press.
There is nothing like a heavy barbell. That being said, dumbbells are a nice break, they let you work on stability more, they're good for off the chest strength, they don't beat you up too much compared to max weights on a barbell, and it's easy to not kill yourself if you don't have a spotter. In theory they also allow a greater range of motion, but most of the clowns I see using dumbbells in lieu of a barbell actually have less range of motion than they would if they touched a bar to their chest. I use dumbbells every 4th week or so on my current training regimen.
doing dumbells helps me get the barbell off my chest. They dont do much for lockouts, i get about the same pump from Dumbells vs Barbells dont see a differences in gains. Howevrer the stabilty it takes makes DB bench harder and a good break. I usually Bench to a ORM using a powerlifting template then for my chest assistance lift i use dumbell bench with my feet crossed in the air it takes a great amount of balance and strength. i benched 260 for my ORM then went on to hit 85 3 x 5. going for 90s tommorow.
I like to do my flat work with a bar and my incline work with dumbbells. Its nice to have unilateral movement to ensure that both sides are working equally.