I have the DK50SE which is on the same chassis as the DK40SE and has the same loader, I love it and as far as I am concerned when talking tractors you want more weight not less, weight is the biggest contributing factor in being able to use implements, many of the old small farm tractors are less horsepower yet they are heavier allowing the tractor to still be able to pull some larger implements albeit at a lower speed. I don't have trouble with my turning radius, if I can't quite make a turn it is simple with the hydro trans to quick back up a smidge then finish the turn.
As far as the brand, Daedong makes tractors under the names, Daedong, Kioit, Bobcat(recently discontinued), McCormick, and Landini. For example my tractor the DK50SE is identical to the Bobcat CT450, they are all simply a different color sheet metal. Here is another thread with a little info on daedong:
http://www.tractorbynet.com/forums/kioti-buying-pricing/239070-daedong-engines-any-good.html
I don't have anything against Kubota as I have never owned one but I have read posts on here about their down sides such as jerky 3pt, and when I was tractor shopping I wanted as much tractor as possible for my available money, which wasn't much, so that put Kubota, John Deere, NH, MF out of the ball park. I don't agree with paying high dollar for a tractor because it has a certain badge on it simply because of "good dealer network", I think all brands have some crappy dealers.
The dealer I bought through was 2 and a half hour drive from me, I have never went back to them for anything, and lucky for me a dealer with multiple locations near me in NorthCentral WI picked up the Kioti line after Bobcat quit the compact tractor line as they are identical with the exception of the loader, however I hope not to have need of a dealer. With the advent of the internet I don't think part availability is much issue anymore and after the 4 year warranty period is up I doubt I would have the dealer work on my tractor anyways as there are plenty of good diesel mechanics around who don't charge as much as the dealer.
I am currently on 5 and a half acres of high land hardwood with an adjoining 12 acres my cousin owns of the same land type, it is tight quarters in the woods and I get around fine, I am glad I bought the DK50SE rather than a 30 or 35 horse tractor as was my original idea.
I also have not found anything short of a massive root ball from a stump I dug out with my 9ft Woods backhoe which I couldn't lift, however I could push it so that's what I did then rolled it where I wanted it. My old boss has a 2004ish NH 30 HP and that loader was next to useless, it couldn't even lift the front of the tractor off the ground with down pressure, I knew from the start I didn't want anything like that.
I say if money is equal or close, when talking tractors go bigger and you can't go wrong, esp when bigger is also going to be nicer, but then I'm quite biased, good luck tractor hunting