aesanders said:
It really depends on the pasture. Some pastures are as nice as lawns --smooth and full of grass. If you cut them frequently enough (say once a month or so, or have animals constantly eating the grass) then a finish mower will work well. You can raise the cut height up to max so your still leave a fair amoun of grass on the plants. Some pastures are rough and full of rocks and only mowed a couple times a year. If this is the case then only a good brush cutter will work. If you have something in between I'd probably side more with the brush cutter. I've seen some beautiful large horse farms that are all done with finish mowers. They really look great.
I've hesitated to stay in this particular discussion because I have only a few months experience, but in that limited time my reasons to hesitate on using the brushhog for just grass are:
1) Cut quality - I am finding erratic cut quality on grass with my LX6, which is nearly new (20 hours or less of use since brand new) and not beat up. Sometimes it does a very good job, sometimes it seems to miss a lot. Often the job looks good immediately afterward but in a day or two I find a lot of the grass/weeds was just bent over and not actually cut off. Now on woody stuff the LX6 is great, slicing right through. It also seems to work better on lush, tall grass than it does on thin mixed weeds and grass, but the latter needs mowing more than lush grass does.
2) Ground damage - I believe I have everything adjusted optimally (tailwheel height with front lower than rear of cutter, links in float position, etc.) but I still find I am often damaging the underlying ground with the brush mower, either from the tailwheel or side skids. Maybe further adjustment would stop this, maybe not. It seems to be a worse problem when grass is thin and scraggly with some weeds, but that is the type of area that, if in pasture, needs cutting and may need repeated cutting. Ground damage to a pasture just sets back your pasture renovation/maintenance, which is presumably why you were mowing the pasture in the first place.
I definitely wouldn't sell my LX6 nor would I use a finish mower on trees and woody, thick weeds, but on thin weeds mixed with grass I find that our riding mower (cheapo MTD) seems to do a better job than the LX6 on my tractor.