Over the years here on TBN, there have been occasional mentions of tractors breaking in half due to backhoes. I think there may have even been one picture of such an incident. I'd say it's a rare occurance for sure and not likely to happen with a 7 backhoe, it's just not that strong. It will toss the tractor around a little but overall it's a well balanced package on my 790. It's probably my least used, but most fun implement. I dug a drywell for a neighbor a month ago and haven't had it on since. That's precisely why I wanted a Deere, frame mount model. The mounting and dis-mounting is so easy.
If you work it pretty hard this weekend, that should show any problems. If none, you'll be good to go for a long time I suspect.
I put new seals in one of my stabilizer cylinders this spring. I had dropped a piece of concrete on the piston rod and it got a small nick. New seals and some steel wool to the rod and it's AOK. I have the seals to do the swing cylinders but haven't bothered yet. They weep a bit which I've heard is common on the #7 due to their location. They're in the perfect spot to pick up a lot of dirt while digging.
Good luck, and post some pics for us. What size bucket is on it?