I have played a variety of the 6 1/2 footers including the 131, 109c and 116. One aspect of the 131 scale is a long back scale on the bass bridge which puts the bass bridge well away from the back rim so that it is not detrimentally restricted in movement. I think that helps a bit with bass response. The 109c was a frequently used scale in the 1890s through about 1910 and usually featured the "yacht tail" which was typically a bit wider than than the continuously-bent scales, though those tend to be wide compared to many makes, but not so much so as compared to the 109c scale, which often includes a very wide left cheekblock because of the very wide board. I am a little less enamored with the Scale 123 which has a less massive plate, though it's certainly stout enough, and some might prefer it's design which allows more open soundboard area, and they sound fine, anyway. I just tend to prefer the heavier plate and one that is full-perimeter, for the inherent structural stability. The 109c and 116 are much heavier plates.
The tail of my concert grand is only slightly narrower than the unusually wide tail of the original Mason CC prior to their narrower versions in CC1 and CC2. Like the Masons, the original Chickerings had massive rims and bracing. I've seen yacht-tailed concert grands with soundboards very nearly as wide as the Boesendorfer Imperial.
One preference I have for Chickering over Steinway is in their use of rib-crowning for the soundboard, where Steinway has used compression crowning methods. With rib-crowning, the curvature of the board is supported by a machined-in curve along the tops of the ribs. The boards seem to survive better over a longer time. Every Chickering I've played still had its original board and without exception, tone, sustain, and projection were still very good, even in a few where the board was not pristine but showed signs of compression ridges or even separations at glue joints.
I have never run into a 119, the 7'6", the 110b at 7'8" with the wide yacht tail, or the later version of that scale with the bent-rim. There were models at exactly 8 feet from about 1880 till about 1920, but I'm not certain of the scale number, but I believe it to be 121.
One aspect of criticism of action design is that in most older models, the action brackets on the action stack are generally made of laminated wood, though this does have inset steel flange rails. The one rail that does not have a steel insert is the letoff rail, which is all wood. Laminated wood is not as susceptible to changes in dimension as solid wood, but certainly more so than metal action brackets. I have not experienced any problems with the laminated action brackets, but would prefer metal for strength, give the choice. Also, many used brass hammer and wippen flanges, which some criticize, up until about 1920 when they changed to wood, doubtless for production savings. I actually prefer the brass for one very good reason--they do not "travel" like wooden flanges do. When wooden flanges absorb moisture and dry out, cycling over and over, that loosens the screws and hammers travel away from centered on the strings and must be aligned and tightened regularly. This doesn't happen with the Chickering brass flanges. Same for the wippens. They stay where they are parked. As long as the screws are tight, they stay right where they were put. Other than those points, the Chickering action from about 1885 forward is pretty standard double escapement. Mine is still using everything original execept for the hammers and shank which I replaced some months back, and in spite of that age, I still find it the most precise and controllable action I've ever played, with whisper soft amazingly easy but with good leverage for FFFF. The keys truly feel like they stay just under the fingertips with a nice firmness, but without any sense of heaviness throughout movement.
I have not heard anything indicating the hammers were any smaller than average for any given size. Those on my concert grand certainly aren't. They're about the same as a Steinway D for size. When I ordered my replacement Ronsen Wurzenfelt, they came in at precisely the same dimension.
I like the 6 1/2 footers better than pretty much anything comparable. Enough so that the preference made me look for a full concert grand instead. I feel spoiled by it and even though it's over 100 years old, many days after practice I get up from the bench and think "wow!". I can't help but respect the engineering that went into the thing such that all these years later it is still possible for me to feel that way. I figure as a former Steinway/Mason afficianado, I'm about as annoying as a result of my Chickering conversion as some recently converted to evangelical religious orders. So you really don't want to get me started. And, also, I figure most such preferences for tone are subjective taste anyway and neither here nor there except to the buyer/owner. But on objective issues of stout and precise construction and good design, I stand by Chickering's historical reputation as "second to none". It's interesting to me how many of the great composers and players owned both Chickerings and Boesendorfers at home, with the odd Steinway thrown in. So I tend to think that's the sort of company they belong among.
Baldwin production pianos bearing the Chickering name have no basis or derivation from any orginal Chickering scales, but rather derive from old second-tier Baldwin designs. I think Baldwin completely missed the boat by using only the name and not the original scales. If they'd really wanted to challenge the top of the heap Steinways and Masons, they'd have done well to go back to C. Frank Chickering's award winning scales.