Since mowing is your main concern I think the B series is the right choice, they are meant to be a mowing tractor more so then the L even when they offered it.
As for the platform flex, they are rubber mounted so some movements is expected, I'm not really a big guy but I have some flex in my 2620. I haven't heard if any problems with fenders or decks breaking either and all the other tractors in this class I've sat on feel about the same.
Hydro pedal, personal preference, I liked side by side pedals until I started using my dad's bx with the above deck pedal and now i prefer it.
I appreciate all the information. The
L3540 was a great tractor but needs to be in the dirt or moving materials with plenty of room to move. I learned that bigger isn't always better so I sold the "L" and am back in the market. Kubota has always been a bit confusing with their model numbers old and new so its hard to know exactly what I'm comparing at times. You are correct about not hearing of a fender or deck breaking so I guess I'll let that issue rest. I know the dollar vs the yen has been an issue and therefore the Japanese may have been cutting back on steel to stay competitve with the Korean companies where the value of the dollar wasn't as much of an issue. Sounds as though the 2650 should be more stable than the 2601. I'm sure it will take a little getting used to and just trial and error as to what I can get away with on the slopes.
If you can swing getting the BH at purchase go for it, I couldn't and ended up building my own as I can't justify buying one right now, but wish I could have bought it together( plus it cost less at purchase).
I would love to have a grand L like yours, but the B fits my needs better with its lighter weight and compact size doing things like aerating and cleaning up wooded areas where the larger tractor wouldn't fit.
I've more thing, the 2650 only weighs about 150lbs more then the 2601 and is only a couple inches taller and about 4" wider.