Actually, many of them can handle big heavy stuff (Tri-tool, Protem, Wachs), and I am not recommending any of them. I am sure there are others. these are three that I have had experience with, and on materials as hard a Grade 91, and as large a 30". They all have advantages and disadvantages. The problem is rigidity and time. Make sure on the big pipe you use a cutter with a big heavy body to provide rigidity. This will directly influence the amount of pressure you can exert on the the pipe end. If memory serves this will be their largest portable units. And make sure they provide training from their techs. Experience is important to achieve efficient and quality results. There are tricks.