Most CUT's run out of traction before running out of power.
There is a point at which a few extra HP is a non issue, but I don't think you are at that point yet. In that size tractor 5HP is a pretty significant difference and I would go with more HP, over the lifespan of a new tractor a few dollars really isn't going to matter that much in my opinion.
As mentioned, you might want to expand your search as $3000 should get you more than just a bit more HP.