Well, I hate to throw a wrench into what has up until now been similar opinions, but....
I have a 15" Walkabout Scout stack. I have never had any trouble carrying the combo or the bottom cab. The combo has a top handle (kind of a thick leather thing) and the bottom has a side handle. I walk into a club with one in each hand if it is a fairly short haul. And I am an average Joe guy at 6'1" 180lbs - 195lbs. (depending on how close to Christmas I step on the scale) Not exactly a body builder. Also, if it is a long haul, I stack them both in a tiny little Magna Cart and it rolls fine and doesn't even strain the cart. So, load in isn't a big of a factor as some might have you believe (unless they just aren't very string to begin with..... not a put down, just observation).
Tone wise I have A/Bed the 12" and 15"combos in a store before I bought. First off, I think volume wise the Walkabout Scout 12" would eat the SWR for lunch. These things can get LOUD! And the tone of the Walkabout head is simply superb. That head gets used as often as my vintage Ampeg V4. Now, as far as comparing the two (12" and 15") here's what I found. At lower volumes, the 12" could not only hang with the 15", but with a little EQ tweeking, they pretty much sound the same. But the 15" can do bigger, warmer tones louder than the 12" to my ears. (I don't begin to know the physics so I'm just going off of what I heard.)
I prefer the 15" for both tone and volume (and the stack of two of them together is GLORIOUS!) but I play louder gigs than you I'm assuming.
Here's my gut feeling. I honestly think that the 12" Walkabout Scout combo will get the job done for you if your requirements are simply to be louder and warmer than the SWR. I think the SWR Workingman 12 can't hold a candle to the Walkabout Scout 12 in any regard whatsoever. I think you will be pleasantly surprised at how these things perform.
Sorry, I don't have any Walkabout 12" recordings. I'm trying to find the CD from a recording I did for a church micing the 15" combo. If I find it I will find a way to post it or share it with you some other way.
Based on what your requests are, I would not hesitate to encourage you to try the 12" combo.
Here are mine from the sale thread when I bought them.
If you're gonna be stupid, you gotta be tough. - My Grandmother