I thought about building a 40th anniversary MTB frame for the upcoming NAHBS but decided that I didn't have the time- that was until my 8+ year-old aluminum 29er frame broke. Along with that, another component company asked if I had a frame they could use in their booth for the show- it all added up to the building of what you see: 650 boost frame in steel with dropper post routing, 1X guides and relatively modern geometry. After riding aluminum for over a decade in the dirt I'll be on steel now- yes, this one is for me.
I elected to use a tapered head tube- I still have to put on the re-enforcing rings as of this photo. My goal was to make something mid-weight- not super light but not over-built. I'll weigh it today. I just built another one last month like this and it was just under 5 lbs. My 29er frame was under 4 so there will be a bit of a weight penalty but since I'll have 650x2.6 tires, I will not be setting any uphill PR's.
I'm hoping with the larger profile tires and a 120 mm fork I'll get beat up a bit less and be able to ride the rocky stuff without being as terrified. The dropper post will be a nice addition.