Good objective reporting, and I cannot fault your stated reasons for preferring the S3. I share those views a good chunk of the time myself. If those are your primary criteria, then you've made the right choice of mount for yourself.
Part of the followup, though, runs toward the more generalized "better bike" variety of argument.
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I can get a Street Triple's worth of fun out of my Speedy...
I'm not so sure, because we don't yet know what a "Street Triple's worth of fun" really means. It's not going to be exactly the same as what a Speedy's worth of fun is, and it's not intended to be; nor is it a question of quantity of fun, but of what kind.
The Speed Triple is a great bike--I know it is from personal experience. That's exactly why I don't believe comparisons between it and any smaller bike can really be too meaningful, because the S3 is unique. And so, apparently, is the Street from what reviewers are saying about it. If two things are unique (meaning, one of a kind) then they must also be
different in enough crucial ways that head-to-head "mine's better than yours" comparisons are just two people talking at cross-purposes.
There is the other side of the coin, whether everyone believes it or not: some kinds of fun are experienced better on lighter platforms! I was just reminded of that in a big way a few minutes ago by my neighbor's 305cc Honda scrambler, which he's gotten out and is working on for the first time in 30 years. Even with the clutch plates halfway glued together and a fraction of the displacement any of us are accustomed to, it's still loads of fun! He's the current owner of my former Rocket III, so he's in a position to appreciate the differences.

Which leads to another way of looking at it: While you can scrape pegs, wheelie, and do all kinds of things on a Rocket III that you can do on the Speed Triple, that still doesn't mean you're doing them as easily or even as precisely as the S3 does them. They're best suited for different
kinds of fun, not different quantities thereof.
Light has its own joys, and I'm looking forward to exploring the Street in-depth for whatever it turns out to be on its own terms--not what its big brother is, because I already know about that.
Variety is one of the things that make the world go around. Ride what you like, but keep an open mind that others are enjoying their choice just as much as you're enjoying yours. Their reasons may be different, but just as valid.