When Briggs took over Simplicity they made very few changes.
I am assuming that it was part of their vertical intergration plan to ensure there will always be a market for their engines.
implicities were never that, Simple, but they are excellent mowers and that one should be around long enough to mow the grass over your grave.
AS time goes by more & more moron lawers keep getting cases in front of bleeding heart judges who award silly compensation payouts to people who really should have either been allowed to die of fined for their own stupidity.
Thus to prove the mowers are being made idiot proof, they get more & more complicated and you can expect this to happen at an accelerating rate.
Simplicity has always been a top end mower so if the perfect design requires 15 idler pulleys, then they fit 15 idler pulleys.
I am always reminded of a customer with an old Bolens.
His father had bought it, when he moved onto acreage and he had now inherited the mower & the estate.
It needed a new belt, the first one that had ever been put on the deck so it had run better than 20 years, but fitting it was a nightmare as there were pulleys & guides everywhere so when the deck moved through it's 6" cutting range the belt run remained almst strait from one pulley to another.
Now days to cut cost they just fit deeper grooved pulleys which wear out belts 50 times faster.
I use a yard crane to lift the mowers up so I can get underneath them comfortably and for tractor type mowers that might mean standing them up near vertical
Inside the shop I use an engine crane for the same purpose.
We use an old Dexion pallet racking beam as a spreader bar and with that I can lift the entire mower 4' in the air.
A younger friend drives his mower up onto his tall trailer then he puts stands under the ramps and runs off the trailer so the mower is sitting about 2' off the ground to work underneath it.
The real question you need to think about is how comfortable the Simplicity is for you to drive now and in the future.
Interesting that you mention Bolens. My Dad had one (can't recall the model) - big thing - huge deck. Unfortunately it wasn't in running condition when my brother and I auctioned off the contents of the house and attached garage. Couldn't even get beyond the initial asking bid of $100. Sad too cause it came with attachments that alone were worth a few hundred dollars.
Good to hear about the quality and durability of Simplicity. It's a tough call. I was a little taken aback when the dealer told me it'd be close to $2k just for the snow plow. Another $900 for the deck. It gets frustrating hearing somewhat conflicting stories from people I've talked to as well as researched online as to the attributes of the various tractor brands. It does seem an almost unarguable point that these old Cubs built by IH were really tough, well-built machines. Having mine for 47 years (with really no major issues up till now) is pretty much testament to that. I find it hard to imagine that any (or at least most) new tractors being built today will have that type of longevity.
I don't have the type of equipment you describe to lift and work on the decks - just me and my aging muscles. I'm so used to working with the Cub. IF the deck on the Simplicity is any heavier, that could present problems. They couldn't seem to tell me much about how easy (or hard) it is to take off the blades. I got the impression that people send these tractors in to them for routine maintenance and service. At least, they sure had a bunch of customers' Simplicities in the shop. That's fine, but I have no means of transporting any tractor. It's amazing to think that, other than my Dad doing a bit of overhaul work on my Cub (wish I knew exactly what was done) maybe 20 years or so ago, other than this recent episode where my brother refaced the valves and did a few other things, I'm betting it was only at a local repair facility 4 times total since I bought it in '81. So one of the big decision points now appears to be....is the tractor basically used up and worn out? If so, putting in a new engine seems foolish. Guys who work with these old Cubs all the time would seem to indicate that it may well have years of use left. A bit like rolling the dice. But then, every day is like that when you get right down to it.