There isn't much I can add to what has already been said. LS makes good tractors for many different dealers so I have no concerns for quality of the tractors. As for the LS, It looks like you would be getting about $7,500 off by buying a 2 year old (possibly less depending on when it was sold) tractor with only 300 hours. That's = to $25 per hour. I just did a calc for my tractor @$25 per hours would be 1420 hours to totally depreciate it. No way would I use that much depreciation for MY tractor, so I think you are getting a fair deal as for discounted pricing.
You would need to look at the wear and tear on the FEL and Backhoe to determine if it is worth more than that to discount. As for the tractor, that is almost nothing in terms of life of the tractor AND it has 3 more years of powertrain warranty so I would not be concerned on the tractor. Look closely at the FEL frame and bucket for warpage, ie does the blade set flat on the ground as you slowly lower it(check it with the bucket flat and with the cutting edge vertical) check the cutting edge for straight or is it bent or bowing in the middle. Check the backhoe for slop in the pins, there will be some but as long as it isn't excessive, it should be ok. Check the hydraulics, will the stabilizers lift the machine up, will the FEL bucket lift the front of the tractor(you have to dump the bucket lip down all the way to do this test, check all the valve controls for function (are any of them loose: there should be little to no movement that does not cause hydraulics to move). If it all checks out good, then I would probably go with the LS for the back hoe since you obviously need one.