I would look into this thing, I read where a commercial mower put these on three of his machines and really likes them. ZTR Lawn Mower Replacement Seat - ZTR Puffer
If you are not interested in this, then I would definitely get a good suspension seat and they do help with a bad back, also I do not know what tires you have on the front, but I changed out my run flats for pneumatic tires and that really helped with the front end bunny hop you can get with the run flats.
Again, thanks for the input. It all helps.
First, I think one of the previous posters was correct about the reason other mowers don't use 4 wheel suspension. Patents. In my opinion, Ferris is selling faster than they can produce them and the suspension is the main reason. There are lots of us old farts out here with big lawns and need to save what is left of our crippled up backs. I have a local Ferris dealer here who told me he can't keep them in stock and sells at MSRP. Eventually, the patents will run out and I think we will see the other manufacturers start producing similar setups. Just my opinion only.
Now, the various suspension seats, kits, etc. I've come to the conclusion after spending beau coup hours searching and reading reviews, that both the Michigan and Puffer units have merit and will surely help. However, these are mostly band aid fixes and what is need is complete redesign of mowers. The reason is, I think, that we have mowers now that used to travel at speeds of around 5 mph which took the bumps without much problem, but now they are moving twice that speed which magnifies the severe shock and jarring directly to the spine of the rider. This equates to increased fatigue and latent injuries that will likely manifest themselves over time with back problems that can plague a person indefinitely.
I don't mean to make a speech, but it probably sounds like it. I still haven't decided whether to use the band aid or bite the bullet and upgrade to something with a better ride.
Meanwhile, I might keep bothering you folks until I get the answer I'm looking for, which at this time is unknown.
Thanks, again.
Deke