Will 5 extra horsepower make a noticeable difference? I've crunched some preliminary numbers and the 2320 is about as high as I can go payment wise.
A couple of comments. First, that sounds like a pretty major storm you threw at the little 1860. But, where you live I imagine serious snowfall is a big part of the equation. So I could see where more grunt would come in useful.
Second, if you do decide to trade for the B2320, your timing couldn't be better. Not only is there a $700 rebate running, but for the B Series there is an additional $300 rebate if the tractor is coupled with an FEL. So there is a total $1K rebate available for cash payers. Even if you plan to finance, the $300 rebate is still available if you take the 0%. So that's some pretty good incentive there.
Third, as for the "5 extra horsepower". I think you will notice a much bigger difference than suggested by the numbers. The reason I say this, is because the B2320 actually uses the same engine as the BX2660 -- the D1005 (1.0 liter). The reason it has a lower HP rating in the B than the BX, is because it is "rated" at a lower rpm (2800 vs 3200). But in this configuration, it makes more torque than the BX version of the same engine. So, it will be running slower (quieter) yet giving more torque than the BX2660's engine. I'd guess you would notice more difference between the BX1860 and B2320 than you would between the BX1860 and BX2660.
Good luck whatever you decide. Keep us posted.