I suppose that I look at the 24 versus 30 hp tractors this way.
The 24hp units are small tractors but with plenty of HP to run the size implements you want to run. The same size tractors can be had with less hp, but typically I don't find any value in smaller engines, and that is especially true given the fact that you are looking to run PTO powered attachments & implements so going down to a lower HP in the same size machine is going to limit your attachment & implement sizes. Your location and climate indicate thick lush grass and heavy snow are both very likely so I would opt for the most PTO hp I could get inside of the tractor size range I chose.
So that said, then the question is does the 24hp class of machines have enough hp or should you jump up to the 30hp class?
You said up front that you are mostly mowing and concerned about snow blowing as well. You indicated that FEL work was a lower priority. You also indicated that you want to limit the mower deck size to 60" because 72" will very likely cause scalping.
Now taking those things into consideration, then it really makes no sense to go up to the 30hp class of machines because you will have so much reserve power that will be unused as to become inefficient. It is one thing to have some reserve power but too much simply becomes a waste. A deer can be easily taken down with a 30-30 or a .308 and neither will bruise your shoulder when you fire the shot. . . but if you take a .416 Rigby and pull the trigger the deer will be just as dead, the noise will likely wake people 2 counties over, your shoulder will be black and blue for a week and a half and there is that quarter sized hole that you punched through the deer that is just a waste of meat. Essentially you are laying out a list of tasks that fall into the 24hp class of machines, you are looking to buy attachments that fit the 24hp class of machines, but you want to put them on a 30hp tractor. I guess I liken that to the hunting example above. A 30hp tractor will suit your needs just fine for a 6 acre property but so will a 24hp tractor. A 30hp tractor will be pretty large for a 4 acre property if most of your tasks are mowing and blowing as you have described earlier.
I have personal experience with both the TC24 and the B2910 so I will share my experience and try to limit my bias. I would also do a few things like measure your garage and consider your landscaping. The TC24 fits in my garage while the B2910 is too tall unless the ROPS is dropped down. The TC24 turns much tighter so mowing actually goes faster because I can get around landscaping with far less back tracking. The ROPS on the TC24, being lower, fits under some branches that the B2910 won't fit under making mowing in the trees easier.
The reality is you will need to decide what you want to buy and how much you want to spend and who you will spend it with. I suspect that the pricing of the machines will be run from cheapest to most expensive in this order: B2410, TC24, B2910, TC29. There will be more than a $1000 spread between the bottom and the top. The two 24hp machines will likely be fairly close, the two 30hp machines will jump up a bit and the gap is likely to be a bit larger than the gap between the smaller machines.
There are a lot of other machines out there, and most are probably very nice machines. Your #1 task is mowing, that would take me to a smaller, lighter, faster turning machine. Your #2 task is snowblowing, I would not go below 24hp for that because it will give you the power to run a 60" blower in heavy wet snow or a 60" deck in heavy thick lush grass. Your #3 task is FEL work, there you might find some advantage in a heavier machine but most any machine has a capable loader. If your priorities were different, and FEL work was higher up the list, then I would probably push for the NH just based on its capabilities and its visibility.
