I said the 25 series has the 62 STYLE keywork (and I KNOW it has the 62-style keywork) - I have compared both the 23 and 25 series saxes side by side (the actual instruments, not just photos), and the keywork is very different on each instrument.
The 25 keywork being much more like the 32 and 62 in it's style. I've still got the old catalogues somewhere which show the clear and distinct differences between the old 23 series and it's successor - the 25 series. The main differences being the 8ve mechanism which is the same as the 62, the upper pillar mounting with three heads on a single stem for the high E, high F# and LH3 keys, the bis key/G# pad cup mounting and the pillar for the LH little finger cluster with four pillar heads mounted on a single stem like the 62.
The 23 series has only lingered on in the US (where they were being assembled until very recently - now production has moved to China), whereas the 25 series replaced the 23 series in the rest of the world in the '90s.
Compare and contrast:
YAS-25L/275:
http://uk.yamaha.com/en/products/musical_instruments/winds/sax/altosax/yas_275/?mode=enlarge
YAS-23:
http://www.yamaha.com/yamahavgn/CDA...mage/0,,CNTID%253D65052%2526CTID%253D,00.html
YTS-25L/275:
http://uk.yamaha.com/en/products/musical_instruments/winds/sax/tenorsax/yts_275/?mode=enlarge
YTS-23:
http://www.yamaha.com/yamahavgn/CDA...mage/0,,CNTID%253D65061%2526CTID%253D,00.html
At the time (in the UK in the mid-'80s), the student sax market was mostly East European instruments from B&S (Sonora/Elkhart/B&M Champion) and Amati (Corton/Lafleur) at the lower end of the market and Yamaha at the top with the 23 series, and all went to high F.
Then Taiwanese saxes such as Jupiter (or Buffet Evette), Earlham, Artemis, etc. were being imported and had pro-style keywork to high F#. Although these were considerably cheaper than Yamaha, they did have the features that were found on pro instruments. Yamaha 23 saxes looked dated in comparison to what was on offer from the Taiwanese manufacturers, though that's not to say Yamaha's quality was lower, they weren't keeping up with the levels of specification.
So Yamaha responded in the mid-'90s by launching the 25 series which felt more like the 62 under the fingers and had the high F# - though I can't see from the photos if they had the low B-C# adjustment as on the 32 and 62. The 25L came in a bit later and had all lacquered keys (instead of nickel plated keys) and then the 275 with an adjustable thumbrest which is where we are currently.