You forgot getting in the same aero position on an mtb than the cx bike.

Truth be told, generally people riding 26-30 lb steel framed gravel bikes don't give a damn about being aero. just like they don't care about speed. or average speeds, etc...

at the same time..... I'd just as soon ride my 26 lb. alloy hardtail than to ride a 26+ lb gravel bike. Swapping out the 800 ish gram 29er tires for a 440 gram 40c gravel tire would make my 29er a way better choice for gravel than those boat anchor gravel bikes.

I have a sponsored friend that also rode her Super X to a high finish at Dirty Kanza, Gravel nationals, Overland etc. She much preferred that over the Slate.

Also Kaitie Keogh rode her Super X also to win dirty kanza.

I know, right? They are 60mm Schwalbe S-One tires aka the big one. (yes they were horrible in the soft muddy patches - too much flotation, and no traction - but they are great on sand).

For reference:
they have 11-16 watts drag (depending on PSI)*
Continental gatorskins have 19-26watts drag (depending on PSI)
My Michelin race tires are 14-19 watts

My goal in this test wat to set the bikes up with similar rolling resistance and aero drag and see how compatible they were, given the mountain bike was heavier, had larger tires and somewhat different geometry.

They were amazingly similar in the first half of a 3 hour ride, but the weight (on rolling hills) just wore me out eventually.

In a short fast race ride, or riding into the wind, the gravel bike would have had the clear advantage with the drop bars. But again - the crossover between rolling resistance and aero is about 12-13mph, so aero isn't much of a hindrance at a casual endurance pace on a gravel ride.

Comparing 40 - 60mm tires - the big tires were super cush and had better traction in the soft (non muddy) stuff.

I wasn't really expecting the weight to make that much of a difference in endurance.

*ps: realistically they are going to have more resistance than 11 watts on a gravel ride, but it is an odd feeling to be riding on pavement at 15mph on a mountain bike and expending about as much energy as I would at 15mph on a high end skinny tire road bike.

Yeah, from what I have read, the top riders in that one are usually on cross bikes. Not sure why that is.
(please correct me, if I'm wrong, LOL).

CX/Gravel. there is still 10k of climbing so in the vein of this thread.. weight will matter. and the Slate is NOT a light bike. very heavy for what 2" of travel that will bob on steep climbs.

It sure is. It's an anvil of a bike at 20lbs for a size XL. Also by your last statement I can see that you have never ridden one. The Oliver with the correct amount of air on it for the weight of the rider and in lockout position will not bobble on a steep climb.

you don't pedal hard enough, that's why no bob.
next!

I did ride one. Felt sluggish as hell compared to my Mares CX and the Super X i also rode. could be the shock, the 40+ tire.. i dunno it felt slow and heavy.. i dont really care though. It has way more going on than I want and the Mares can do gravel and cx races and easy to work on.

The feeling between my Tamland and SuperX while climbing is noticeable. Whether the 6lbs difference is the reason, or the more aggressive geo, or whatever, is irrelevant to me. The SuperX is just more fun to ride. It's light and snappy and fun. It feels like a road bike with 40mm tires, and that makes this roadie happy.