If you're going to be doing anything more than just trimming up small branches and taking down very small trees (12" or less, with most of them being less) then an MS180 will do the job. But anything larger than that will require more saw. Period.
Since you have not only a 1/2 acre lot but a wooded 54 acres, I suspect that your needs will end up exceeding those of the regular suburban homeowner. So, with that in mind, I doubt that one saw will meet all your needs. I have written this before, but here it is again:
I sincerely belive that anyone who owns land, heats with firewood, or otherwise has cause to use chainsaws on a regular basis will end up needing three saws to meet all of their needs and not be using a saw that is either too big or too small for the task at hand. Though you can do amazing things with super-small saws if you try hard enough, there is a reason that larger saws are made. Over the years since my childhood I've gone through a fair number of saws to finally settle on three machines that meet my needs as a recreational woodcutter:
1. I have found that a small 30cc-ish saw is really useful for trimming up the odd small branch that falls down in a storm, to prune trees, to trim yard waste to length for municipal disposal, etc. For me, this is also the saw that sits on the ground next to the chipper when I rent one; it is used to trim things that are oddly shapped and won't feed properly. I've been using a $90 HomeDepot "refurbished" 30cc Echo top handle in this capacity for years and couldn't be happier. Since these are not super-powerful saws, the trick is to keep the weight in the 7-9lb range and not try to make them do something they don't want to do. Along with the small Echos, Stihl's MS170/180 and Dolmar's 401 (though it has an edge in displacement, its pro-saw magnesium case keeps the weight down!) would also be in this category.
2. I have also found that there are instances where a larger saw is useful, but a huge one isn't necessary. After trying a couple different directions, I've settled on the notion that a 10-11lb 50cc saw is ideal for my needs, and probably for most people's needs in this category. This kind of saw is small and light enough for larger "around-the-house" tasks, but can still do firewood and even cut your "big" saw out if it gets stuck. I used an MS290/20" for years, but got tired of it weighing so much and now use a 026Pro/16" for this purpose. Husqvarna's 350 and 353; Stihl's 250 and 260; and Dolmar's 510, 540, and 5100s would fit in this category.
3. Lastly, if you have any serious cutting to do then you will want a "big" saw. Sure, you can cut from both sides of the tree with your 50cc, but it will take all day. I'm very pleased with my 79cc Dolmar, wearing either a 20" or 28" bar. Husqvarna's 372, 385, 570 and 575; Stihl's 440 and 460; and Dolmar's 7300 and 7900 would fit in this category.
Obviously this just my opinion, but I think that it pretty reasonably meets the needs of most frequent, enthusiastic saw users without going too crazy. You may find that your needs can entirely be met with a 30cc and 50cc saw, in which case you can skip the 70+cc saw altogether. Just be open to the idea that having a couple saws has definite advantages and will make you a safer, more efficient saw user than the guy who tires himself out trying to make a single machine do everything.
