The AT seems to take as much force as a model M to depress the switches or more. The XT seems a bit more pingy and takes less effort to depress the keyswitches.
I am basing this off of-
2x model F AT boards
4x model F XT boards (one board has a slightly different color in parts and requires slightly more effort to depress the keyswitch, I do not know yet if it takes the same effort at the AT board yet)
2x model M (grey label) boards
3x model M (blue label) boards
If I ignore the layout, I really like the XT almost as much at the M (maybe more...maybe) and I actually dislike the AT.
There is also a spring vibration in the F boards that I do not care for. A vibration that lasts after the keypress. The M does not have this that I have noticed.
The switch feel and sound seem a bit more crude in the F boards, but are still really, really nice. The M feels and sounds more refined (but less robust). But you could take out a rioting crowd with the F's. It's a barbaric and brute board =D
Actually there are real differences between the PC/XT Model F and the 84-key PC AT keyboards. Having gone through a dozen or so PC/XT Model F boards, I've decided to keep only one for the sake of nostalgia. The 84-key PC AT keyboards have smoother key action than the PC XT keyboards (yes, it's a fact JBert) and a layout to which most touch typists can easily adapt. The 84-key PC AT keyboard has the most glorious mechanical action of any keyboard ever produced.
The PC/XT keyboard layout cannot be ignored if the intent is to use the keyboard for any practical purpose. That layout is absolutely worthless to touch typists in the US. PC/XT Model F fans will need to buy a dedicated XT to AT converter, more evidence of it's worthlessness to most people.
I have seven PC AT 84-key boards. They do require slightly more force for the key presses than the PC/XT Model Fs, but definitlely
less force than the Model Ms. I have easily validated this fact multiple times using the ripometer.
My Model M collection is up to around 15 or 16 ranging from an early Jan 1986 production model 1390120 to several NIB Lexmark made keyboards. While there is always a subjective component to everyone's reviews, most people who have typed side-by-side on an 84-key PC AT keyboard in good condition and a Model M find the Model M experience dull in comparison. Um, actually the Model M falls flat on it's face when compared to the 84-key PC AT keyboard.
The Model M uses an ingeniously simple mechanism (the buckling spring) with membrane technology. The fact that the Model M was cost engineered to improve IBM's profit margins on sales of bundled systems has been well documented on this forum.
So either you have crappy 84-key PC AT keyboards in poor condition, are not a touch typist, or have personal preferences that differ from many of us.
Out of all the hundreds of excellent keyboards produced over the years in the US and Japan, the original IBM PC AT 84-key keyboard (with buckling springs over capacitive contact key switches) is the most venerated keyboard on the Japanese and Korean keyboard fan sites.
So go ahead and keep trash talking the King of Keyboards pal. You are actually doing me a personal favor because the fewer people seeking the King of Keyboards, the more for me