I own a 29D without SuperSteer. I have about 100 hours on it and use it primarily to mow, plus other odd jobs around a wooded 4 acre lot. I have a FEL, 6' 3pt disc, and other standard attachments.
BEFORE you draw the wrong conclusion and to set the record straight...I love my tractor and what it does for me. I look forward to using it, but you asked for my opinion!
I bought without SS primarily because the dealer gave me a good deal on this model he had in stock. (No SS in stock) He said it would be about $900 more for SS. SS was intriguing though.
I find the turning radius fairly tight without SS, can't imagine what SS does...has to be pretty darn close to zero turn? I see no need for SS for mowing and I have quite a few trees and other obstacles. Funny thing, it seems like the 29D with 72" MMM can almost cut as close of a circle as my retired 12hp MTD with 42' deck!
The only other advantage (disadvantage?) would be the automatic 4wd feature. I'm sure the others will comment on this, but think of this...(NOT a bash on NH) I have hand plenty of little things go wrong on this tractor. (Not enough to be real ticked...just little things) These little things seem to be related to the new gadgets and features on the tractor. I am glad I don't have SS and the associated features as it would probably be just one more thing to break or act up.
It will be interesting to see the mechanical state of these Boomers ten years down the road. It seems that NH has got the basics right, but look at all the posts complaining of problems. (Hydro pedals, hood latches, cruise control, etc...) One needs to ask if we have ticking time bombs in relation to these advanced features. Will all this great stuff still work in 10 years, 20 years+ or is it going to fail and stop working???
Raised in a farming environment, my family still runs Allis Chalmers, International, and Ford tractors from different generations. (8Ns, IH 1466, Farmall A and H, Ford 5000 and 8700) Basic iron that gets the job done and has for 30+ years. No real problems and thousands of hours on the equipment. Can we expect this from the Boomer?
Bottom line from me: I don't see a need for SS, and would not pay extra for it on another Boomer.