Well being that I own a 2305 and a 2520 I thought it might be fun to compare the two. I'm not going to get into the specifications directly as you can compare them in another thread.
And I am not going to go into detail of why and how I come to buy them, as I have explained that in the following thread.
Let's start with some background of my situation and intended uses. First off, I currently have two properties that require maintenance with the use of these machines. They are located with in a quarter mile of each other. The first has some trees, house, out building, and a little over an acre. The second is my shop, few trees, and is 2.8 acres. I mow, weed spray, and fertilize all four acres. Two thirds of the properties are sloping grades, alright HILLS. There is some talk out there on other boards about the "instability" of these machines. Trust me I have had these things on side grades that I definitely took notice. I think they are more stable than people realize. I do not have fluid filled tires but, I do use a weight box with the loader. Also, keep in mind that I upgraded to these tractors from 20hp Wheel Horses.
Which now brings me to my first point; I would certainly put the 2305 on a steeper grade sideways than the 2520. I feel the 2305 has a much lower center of gravity. When you take into account the foot print of the machines they are very similar. At least the width is with in a few inches, the 2305 is actually wider on the front tread width, and the 2520 does have the longer wheel base.
All my attachments are interchangeable between the two tractors with the exception of the decks. I run quick hitches for easy connecting. I have run the loader on both and the differences are as noted out there on the web, with the speed and power going to the 2520. If I have any serious dirt digging to do I definitely will use the 2520 as the extra machine weight is the real advantage. I am not one to worry about any speed loss that the 2305 has but it is slightly slower for the loader controls.
In terms of mowing differences, the 2305 has a 62C deck while the 2520 has the 72" deck. They are definitely different machines in this respect. I basically can mow either property with either machine, and I have done it. However, the 2305 is agile and more maneuverable and best equipped to mow the acre parcel with the more obstacles. The 2520 is perfect for the large open 2.8 acres. Each will do either job. They both provide excellent cuts with their mulch kits. They both are very easy to mount and remove their decks.
The 3pt hitches are a big contrast. They are both category 1 but the 2305 does not have position control. Though I can work around this it would be a nice feature to have on both machines.
Each tractor has its own sound and smell, although the 2305 seems to run quieter. Though it won't be a largely noticed difference by most, the gearshift levers are on opposite side of the driver. This is a real annoyance for me as I own both machines and you find yourself reaching in the wrong place when swapping machines. Another difference is the 2520 does have lighted indicators on the dash for the 4wd and pto engagements, where the 2305 does not. I do like the indicator feature for the 4wd, it is just handy. The pto indicator is not that big of a deal, as you know when your attachments are running. The difference of the engagement lever for the 4wd on opposite sides of the operator is not a problem just different. The ROPS's are different; the 2305 does not fold down where as the 2520 does, not an issue for me either.
They are both comfortable to drive. They both do all the tasks I require of them. It really comes down to minor differences, they both fit well within their size group. Of all the tasks I do, either one will do the job. But, as long as I have the choice I definitely do consider the machine for the task. For example, snow blowing, tilling, 60gal 3pt sprayer, and heavy loader work, the 2520 will get first call. The dedicated tasks for the 2305 are the brush, 3pt spreader, and vacuum trailer. They both are well suited to my properties and task needs, they definitely are not the Wheel Horses, I think I'll keep'em.