I'm in a similar situation as you on my 2.5 acre parcel. I think usage is the key point here. I'm going with the CK25 gear drive because my primary usage will be digging. The heavier tractor and equipment will suit my needs better. I mow with a JD425 HSD, and would never go back to a manual tranny for mowing again!
I also considered how easy it would be to re-sell. This will depend on the demographics of your area. I live in an area that is a mix of "estates" like mine as well as small farms. So, I thought the larger tractor would appeal to a wider community if I ever were to sell it, which I have no plans of doing. But, you never know. The horsepower to weight ratio favors the CK20 for mowing, and the size of the CK20 makes it very maneuverable.
If maneuverability is important to you, I suggest you also look at the new TYM 273. I test drove one and was amazed with its turning ability. It's shorter than the CK20, and has a lot more horsepower. Backhoe and FEL were excellent quality. But, it is a little lighter than the CK20.