I don't understand a couple of your remarks. Changing implements is easy, takes 10 minutes or so, faster and easier if you buy a "quick hitch", I have one (quick hitch) but don't use it anymore as with the adjustable 3pt lower link arms it's almost as quick without it.
I have a quick hitch on my Yanmar 2210. Serves very well, but it probably won't be a factor with the new tractor. I'd love to have adjustable links, but it moves me into a class of tractor I may not be able to justify (20 series).
And, I'm well into my "social security" years.
In good health, I hope. I've watched many of my older friends and neighbors experience significant decline in strength and flexibility, due to both age and disease. In fact, some of my tractor time is dedicated to helping those folks with projects they can no longer handle due to their physical limitations.
We all hope for the best, but have to play the hand we're dealt.
As far as switching from the backhoe to other implements that's not something one would do on a daily basis "normally" although from what I've seen the Branson hookup is as easy as any and takes probably 30 minutes or less(not ncluding the 3pt system). Those here that have a BH can certainly give you that information. But, if hooking up the BH to use, I think I would figure my "workload" for that item in particular and leave it attached until project was finished. You're also going to have to return to wherever you took the backhoe off cause' you aint haulin' that around with you. Also the remark that other makers have figured a system that doesn't require the three point arms to be removed would have to be a three point attachment type BH, you can do that on a Branson but it's a poorer setup than a frame mounted type. If you know of a tractor with a frame mount BH that can be installed WITHOUT removing the three point system please let me know which one, as I know of none.
As best I can tell, from dealer convos and online research, including watching videos and asking questions here on TBN, the LS X30xx and X31xx series tractors do not require removal of the rear 3pt hardware to install the backhoe. There are additional fixtures in the frame and subframe that don't require the lift arm attachment points. The 3pt lift is set in the max-up position and remains out of the way. Not sure about other makes, but I can't believe LS was the first to come up with this.
There's another thread floating here about how badly setup the rear lift pin removal process is on the 20 series, including seconded comments like "badly designed."
Believe me, I really like everything else I saw on the Bransons, but this is a limitation that's hard for me, because I do switch tasks frequently, have to move around the property a lot, away from the niceties of paved work surfaces. The wife may ask for a trench or a stump removal and then that same afternoon, I'm grading the driveway or mowing the roadside. I have a full time job that doesn't involve the tractor, so I have to fill up the seat time as best I can. Ease of implement flexibility helps. That's just a reality of my life. Not suggesting it's your reality.