I think people get too hung up on POWER. I have an ecological restoration company and we spend all winter clearing brush. For anything less than 8" my preferred saw is a MS200 with a 14" bar. Its light and easy to work with all day. I also have a MS250 which we have swapped out to a pico chain and 14" bar. It really rips for limbing, in addition to the higher chain speed the smaller bar/chain saves significant weight, though it is noticeably heavier than the MS200.
Even a small, inexpensive saw can be a great work tool. 6 years ago I was working for another company and they bought a MS180 as a lighter saw compared to the standard MS260 we worked with. After a few days of snarky comments about it being a toy, our attitude changed and we would consistently choose the 180 over the 260, it was MUCH lighter, easier to work with all day and not be tired, and really the cutting speed on small diameter stuff (most of our cuts were 6" or less) was not that different. We did put a lot of wear on that saw after 3 months of daily use, its clearly not intended for that.