Ha, Ha...may not be any of us that have ever ridden an SS 440. It dawned on me reading your post that the only Yamaha I have ever ridden in my life is my own 83 Vmax.
Those red Yammis are sure cool looking.
Since the snow is gone (what little we had this year) I will take the time to throw out some wild guesses.
I suspect the Kawi rear suspension will offer a bit better ride. All the press agreed back in the day that they were the best rear skid available in their "Rode Reports"
This was before the newer LTD Vari Ride style skid was introduced on the 80 LTD.
I forget which year Polaris 1st offered the 340 TXL Indy to the consumers.....1980? But the "Rode Reports" in 1 of the magazines said that the Kawi LTD was the only leafer that hung real close to the Indy through a rough section.
Yamaha didn't seem to have a very remarkable suspension during those years, until they introduced the Pro Action rear skid in 1983 on the Vmax and SRV. Now, it's a pretty darned good riding skid.
Owning my Vmax for 25 years, I know Yamaha gave up on their own clutch and had Comet provide the clutches for the new 83 Vmax and SRV.
They continued to develop their own clutch and eventually got it working well.....but on your 440 fan cooled SS's, I'm sure the Yamaha clutch works fine.
I'm kinda a fan of the Kawasaki drive clutch. There is definitely WAY more tuning components available for Comets, Polaris, etc...but if the Kawi clutch has good bushings and is maintained ....and aligned properly, it sure seems to be kind to drive belts.
My Vmax is the biggest pain to work on of any sled I have ever tinkered with....they are kinda known for that. Every component is very high quality, but they used a million nuts and bolts to put the simplest things together. Like any thing, once you do something a couple times, it becomes much easier.
But, those SS 440's are probably a lot easier to work on.
I'm sure the Yamaha's have some very positive points in their favor. Yamaha definitely knows how to build 2 stroke motors!
It's curious that both the Intruder and the SS 440's were marketed initially as really hot sleds.....the 79 Kawi brochure had a picture of an Intruder with it's nose high in the air, with the bold heading "out to launch"
In later years the LTD and Interceptor were added and the Intruder became more of a "family" sled.
Your SS 440's started out the 1st year a bright ,racy red, then became toned down to a milder silver and blue. I suppose the manufactures realized with everyone making some hot liquid cooled models it didn't make a lot of sense to market fanners as really "hot" sleds.
I'm sure you will enjoy those 2 red beauties....
I'm just throwing things out there for the heck of it since we can't talk about riding for several more months.