We have two UY's now and I wasn't thrilled at first, but now I like it as I have June and Dec which allows me to book trips using points from the UY that fits better for travel.
We own at BWV and BLT, our two favorite resorts. I have both BWV and BLT in the Dec contract and just BLT in June, with the eventually hope of adding on BWV with the June UY.
It's not that hard to manage so far but we own enough in each contract to book what we want the way we want, so that helps. We don't necessarily need to use banking/borrowing to make it work so I am sure that could play a different role.
When we originally bought with a June UY, summer and fall was our main time of travel. Now, I am finding I love to get away for Memorial Day weekend--its when we get extra days off if we don't use all of our snow days--and a June UY is not good for that at all. Now that I have a Dec UY to pull from, it makes it a lot less stressful to book those trips, knowing I might have to modify it come April 1st, depending on what happens in the winter.
If you are summer travelers, then having a UY that works for June/July trips might not be a bad thing.
Good luck!