I've read reports that the Unicomp keyboards are a pale imitation of the Model M. Feel is different; weight is lighter, etc.
The case materials and weight are certainly different, but overall I think Unicomp keyboards are still very good. The switches themselves aren't purposely different, but some difference in key feel can be explained by a known change in blanket (the rubbery sheet between the buckling springs and the membrane assembly) material that some even
actually like. In my opinion, how you view them comes down to a matter of perspective - an original IBM Enhanced Keyboard (standard Model M) from their 'prime' era could cost between
$500 to $800 adjusted for inflation. A Unicomp keyboard is 4x to 6x cheaper than that, but they're far from 4x to 6x worse. That original IBM price would essentially be unmarketable today, and even some "half-way" compromise between price and quality for Unicomp would probably raise prices to the point they're not competitive with the reproduction Model Fs. Very specifically, the older Model M casing people prefer was also usually made of PVC, whereas Unicomps are made with PC+ABS. PVC seems to be
increasingly regulated and discouraged so a return to that is unlikely.
Unicomp's quality has also changed throughout the years, with highs and lows people may remember. IMO, Unicomp hit its nadir in the early to mid 2010s. But with the New Model M and Mini Model M bringing new life to the casing (as all the other models are produced with old, worn tooling), although not perfect, I think Unicomps are the best they've been in a long time. Given native USB support and warranty in mind, I have no trouble recommending them.
YMMV though, as I prefer the rubber dome Model Ms like a weirdo
If you prefer rubber dome Model Ms, you might like the
"buckling rubber sleeve" ones!
Whilst not widely talked about, a large portion of the Model M family used this design as a slimmer and quieter counterpart to buckling springs. The IBM Models M4 and M4-1 are probably the 'token' examples of them. If you've ever tried an early IBM ThinkPad with a Model M6 or M6-1 keyboard (like 350 to 365, 700 to 755, Power Series 850 or RS/6000 Notebook 860), you've pretty much already tried one. Toshiba, who bought IBM Retail Store Solutions in 2012, still sells Model M derivatives with them in the form of point-of-sale keyboards to this day with the likes of Walmart being one of their customers. IBM and Toshiba POS Model M keyboards are pretty cool in their own right (left: IBM Model M9 RANPOS Keyboard, right: IBM MCANPOS Keyboard):
Just for fun I weighed them (slow morning)
The Unicomp is 3 lb 13.6 oz
True Blue is 4lb 8.3oz
So not that much difference. I wonder where the actual delta lies.
The difference is probably a combination of the change in case material (aforementioned PVC to PC+ABS) and exact thickness and weight of the steel backplate.