OK... I'm going to throw in my 2 cents since I was kind of in your position a year ago.
The fall before last... I was in need of a new tractor/mower for my property. BUT, since it was fall... I figured I could take all winter to figure it out.
A) I was mowing about 2 acres and I was using a small "Turtle" or rear engine rider. I was beating the crap out of it, but it was doing well. (but was on it's last leg)
B) I started looking at the normal "Box Store" tractors, and after digging into it... I wasn't happy with reports of the transmissions only lasting 4~5 years. So, that made the $2000~$3000 tractors disposable to me, since they had no re-sale value, and to replace the trans was just not cost effective. (Why replace a $1000 trans axle when you can only sell it for $800 after 5 years??)
With those 2 points of information... I started moving up the price range. I found that once you hit the $4k range... then you could get a transaxle that was at least serviceable. (drain fill, filter) But they were still light weight.
SO.....
C) Since I was going to spend the $$$, I wanted more capability. I do have a hilly yard, so I wanted 4wd or at least a locker. From there I started looking at the John Deere, Husqvarna, and Kubota. I found that the JD were kind of overpriced for what you got. So they were eliminated. that left me with 2 choices... the GR2110, and the Husqvarna R322T.
The Husqvarna R322t is a very cool articulating rider, with the mowing deck out front. It's 4wd, and semi-industrial. Every report I saw on it said it was reliable and the mowing was phenomenal !! (like a golf course) You can also change the deck out for other implements. (Broom, plow, snow blower....)
The GR you already know.
As I was on my final decision... I was getting ready to buy the Husky. It was half price over the Kubota, and it was everything I needed. (But the Kubota Diesel is nice) So... Before I wrote the check... I went down to the Kubota dealer, and looked around. At that point, I realized that the BX1870 was actually cheaper than the GR2110 !!!! Even adding the 48" deck, it was only slightly more. AND, after talking with the dealer... I found out that the GR was not ground engaging. SO, at that point, I realized that it was a $10k "Lawn Mower", and not a "Garden Tractor". Then Kubota was running a couple deals. One was a simple rebate of $700 on the BX. Then, there was a $1500 credit if you bought 2 implements. (for me that was the FEL and the 48" deck) and then the dealer gave me a few $$ off. (FYI: this is the time of the year they run the deals)
SO... I took a step back and thought about it. The husky was $5k and the BX was going to be $11k. BUT... the thing that pushed me to the BX was the financing. I could get 0% for 60 months on the BX... but had to write a check for the Husky. Because of that... even the wife (who originally thought I was nutz for even considering an $11k tractor) said OK
So yes... I went from needing a basic lawn tractor, to a BX. And I'm glad I did.
With that all said... if your budget is $5k... and can't move to the "free" 0% financing that comes with the BX... I would get a new Husky over the used GR. The Husky is a simple machine that can mow better than most other machines. (and it can be ground engaging)
That's my story and I'm sticking too it.
http://www.husqvarna.com/us/products/riders/r-322t-awd/967032102/