5687 tube

I have a couple of questions about the 5687 tube:

1) What is the approximate life span of this tube? They run extremely hot, making me think they may have a shorter life span.

2) How important is this tube to the sound of the component? For example, my amp uses 2 5687s, 6 6922s, and 8 KT88s. In terms of bang-for-the-buck, where would you put your money? Into the 5687s, 6922s, or 6550/KT88s?

3) Does anyone have some info about various 5687 tubes and their relative merits in high-end applications? I currently use a Raytheon JAN 5687 in my amp.

Thanks in advance.

1) 5687 have good servicable lifespans comparable to most octals. 9 pin minis usually last a little longer then octals (this is a gross generalization, of course), so you can say 5687 aren't as long lived as most 9 pin tubes.

2) It's hard to say how much of an impact the 5687 will make on your gear. It depends on how your gear is designed. If the 5687 is used as a high gain device, it will have a big impact on the sound. If it's a low gain driver, it'll have less of an impact.

3) Raytheon 5687 are nice tubes, and actually my favorite 5687. It's the most tonally neutral of 5687s in my gear. The Raytehons also have some of the best spatial seperation for htis tube type. All 5687 are relatively warm, full, and dynamic. The Tung Sols are the smoothest (especially the ultra rare flat plate variety), the RCA bronze plates are the warmest (big round bass), GEs have a more aggressive treble, the regular Sylvanias are solid performers with nothing really noteworthy about their reproduction, while Sylvania Gold Brand are fast and one of the most neutral 5687, but some regard it as lean. How was that for a run-on sentence?
I concur with Mr. Whoopadeedoo. I run 5687's in my Audio Note Neiro. They have a tremendous influence in THIS circuit. The TungSols are pretty nice for the price.
Thanks for the responses. My gear is a Sonic Frontiers Power 2 amplifier. Would you say that the 5687 tube quality is critical for this application? Or would money be better spent on the 6922 and KT88 tubes?
Seeing as how 5687 are the cheapest tube type you're using, it wouldn't hurt to invest in a pair or two. Six 6922 and four KT88 will cost you A LOT more then any two 5687 can (except for the Sylvania gold brand and the commonly substituted 6900). I suspect the 5687 is the first stage gain driver in your amp, so it might make a meaningful difference. But as I said, the Raytheon you're now using is a nice tube, and unless it's aging, your money might be better spent elsewhere.
I've also heard that a 7119 tube might also provide excellent results.
Thanks for all the responses!