SED Winged C el34. Help

I am tube rolling my Manley Snappers. I have heard many good things about the Winged C's. I have a few questions.
Are they reliable? I bought JJ el34's and the were like hand grenades in my amps. They blew and took out the tweeters and the woofers in my speakers! Ouch.
So I went to the EH 6ca7 at Manley's suggestion and they
have been reliable. However I would like to try the winged C's, but not at the expense of my speakers.
Also, where do I buy them. I saw a thread that said not to get the Svetlana version so I want to make sure I get the right tube. I have shopped at Tube Depot before but they don't sell them. Upscale Audio does but I have seen them for less at other dealers. Can you reccomend a good dealer?
I would also like to hear from those with experience with these tubes as to whether I can expect an upgrade over the 6ca7's.
Thank you, Scott.