Have you considered eagle?
Weight weenie exercises are modestly inane on bicycles - the bike's a relatively modest contributor to total rider/gear/bike weight - last time I looked at that, my relatively heavy bike was about 16% of total system weight when riding.
I said I would never go eagle but I think I just bought a bike with eagle. crap.Eagle is dumb. Just drop down to a 26 or 28t ring and you can rock 10 speed for dirt cheap.
I'm stating my concerns based on miles and experience rather than net babble. I try to replace chains at 75% wear. Currently running X01 with an E13 cassette. If I were to try it from scratch, I'd want 2 x 9 or 2 x 11.not all cassettes are that expensive (you can get them cheaper, i paid $150 for the eagle gx i bought for my extra wheelset, 11 speed is cheaper yet), if you keep up with the chains you dont wear out the cassettes that quickly either (hell i dont even think the chains are that terrible, i got over 1200 miles out of the last eagle chain on my primary mountain bike).
chains are slightly more expensive but still not terrible . . . . . you do what you like, but alot of the concerns you read about on the internet are blown way out of proportion.