18ga is still pretty soft. I wouldn't try it with #12...
I get the point about solder fatigue, but you would get that with stranded wire too... if the solder was taking weight. With the solid wire it isn't.
Securing the wire with putty also makes stranded wire secure, no?
And many of the tweeters I have used have the terminals on opposite sides.
For the record ... I did not say that using stranded wire is bad. I simply explained that I use solid wire and why.
Only your own experiences can answer that. The opinions of other are useless in this matter. But the stage you are at now, I would say don't sweat it, a safe and secure connection is the important thing.
You're kidding... Right?
There's a ton of science around wire, connections and the way it works. It's not a matter of opinion by any stretch of the imagination.
