I suspect that I'm not the only ST owner with a 2nd bike, owned for a different reason than the ST. What's yours, and what is your reason/excuse?
I'll start.
I mentioned my MT when I first joined, so I might be repeating myself a bit, but I have a '08 Yamaha MT-01, black with 10000ks on it. I owned it before the ST, and it was the reason that I got the ST. My reasoning was that after 100k on the back of the MT, my wife was a bit uncomfortable, as there's not much to sit on. Nowhere near as uncomfortable as my 1100 Katana when we got married, as she almost had a few off's off the back under hard accelleration, hence the ST with it's lounge type comfort. If she comes off the back of it, I'll probably need a new topbox.

Although the MT can tour, it's more a fun bike for just me, whereas the ST tours, holds luggage securely, and will allow me to take my son on longer runs as well.
Both bikes live in the same shed, they don't fight, but I'm sure that the "wife" bike gets jealous of the "mistress" MT when I take her out. Actually, that's a pretty accurate simile of them both! (the bikes that is....)

I could also mention the other bikes that are under the house (50's something AJS 350MS with 500cc topend, and a Cinnamon 1974 Yamaha TX650A), but they don't count as they are both in boxes.
I'll post a current photo of my two working bikes shortly,