i never had v-beam but have had ipl's for years and it works really well for me. the best results i get from it are on a higher setting (they only up the setting when they know what your skin can handle) and 3 passes on each spot. it can take at least 2 sessions or so but its worth it. i only pay $130 a session where i go so its worth the money and its such a quick procedure. i used to go during lunch and then come right back to work.
i have IPL photofacials, my derm basically does the following - cleanses, used some sort of exfoliation gel which she leaves on while my face steams for 10 mins or so (it smells weird like fish LOL), then adds this neutralizer to prepare for the IPL. She also does very gentle extraction of blackheads but never picks or anything (just makes it worse anyway) then she puts on the gel for the IPL, zaps my face with it (its an Ellipse machine) and it has many benefits. I noticed she picked the 'acne' program last time, its basically photorejuvination but with the additional benefits of killing of acne causing bacteria and it really helps with my reddish marks as well as any small acne scars (mine are very minor) because the heat helps with collagen production. If she thinks i need a peel she will add a 7.5% or 15% ++ TCA peel and i peel for a few days which also helps with marks. I would say those IPLs are very good for acne marks but you see real differences are a few days, you look a bit brown after in patches. I find doing this once a month is good. When i first started going to her i had to do 4 spaced about 10 days - 2 weeks apart and it really cleared up my moderate acne at that time. It was getting severe and she got it down to relatively clear.