I like Triple Se7en too. It's good high performance powder and probably my second favorite for use in sidelocks. Here are MY Swiss PROS:
1. Consistancy. It's the most consistant powder I have used. Shot to shot velocity is very consistant.
2. It's HOT. Of all the powders I have used, I get the highest velocity using Swiss blackpowder on a grain to grain basis. It gives much higher velocity than Goex, WANO, or Pyrodex and only Triple Se7en is even close. This is important to me as I can use LESS Swiss and still get higher velocity than other blackpowders.
3. Ease of ignition. Compared to Triple Se7en I can promise you will have much fewer ignition problems. Ignition is practically 100% even when I'm not perfect.
CONS....are there any?
Triple Se7en is cleaner.. HONESTLY I have to say that Triple Se7en shoots cleaner....a good bit cleaner actually. I have to swab between shots more with Swiss or any blackpowder for that matter more than with Triple Se7en. But CLEANUP IMO is about equal.
EQUAL
Corrosion...
HONESTLY...I can't tell ANY difference between Triple Se7en and Swiss. I have actually been SURPRISED that there is little difference. I have in fact found Triple Se7en to be very corrosive when guns are left unattended after shooting and really see no difference in it and blackpowder.
I don't see how you can do WITHOUT blackpowder if you are shooting flintlocks. You could use fffg in everything up to your 20ga where I'd certainly want to use ffg.
I always buy my Swiss from Grafs.com.