Being that the UForce is made for work, not so much trail, you have to assess your work needs, then decide. I live by what my dad always said about stuff like this. "It's always better to have too much...then not enough or..It's better to have and not need..then to need..and not have" I would go straight for the 1000 
I respectfully disagree. In days of yore, I could go 70-80 miles on less than a tank of gas on 300cc SUZ King Quad. Then came the "fad" became bigger and bigger engines. Many a time I met someone out in the mountains/forest worried about getting back to camp cuz running out of gas. I even pulled a few out of the mountains on my lowly 300cc.
I think that "Cost IS an OBJECT". A 1000cc any-brand is a big chunk of $$$. Regular use is also higher cost than something smaller. While a "454 8-liter" engine is a blast for those "blast seconds", it is not very practical.
I like an ATV (or SxS I don't have - doesn't fit in trailer) for what it does without pushing it to absolute limits. My 300cc SUZ lasted and worked its azz off for 30 years. "Worked" meant just that, but not abused or beat to hell. I like to have a good time on my CF machine but can't afford to break it often, if ever. I sold the SUZ last summer still working although a few problems to get new CForce 600T.
Perhaps I am just at the other end of the spectrum. I use what I have and understand or define the limits of the machine. While "in some cases" bigger is better, it is not always true. If someone needs a truck, then just buy a truck and forget a SxS. Maybe this is brutal thinking, but I usually plan for the worse case scenario and (almost) never get into trouble in the forest/mountains.
Others have different opinions, fine. A review of expectations, what you will do with it, and other demands (really requests for Bang-for-the-buck) need to be applied to any purchase. I don't do DEBT or payments at all, gave that up for Lent years ago. Just a different strain of thoughts and values.
JetFinn asked the question, I post my answer. To each his/her alone.
YMMV