Just to clarify a few points, I think the above analysis is not correct.
Valhala is designd for .MIL which uses MLOK not pic rail. This can be setup 400g installed. Adapter is 1.5 oz and ther is no 2oz pic rail segment needed nor the 4 oz pic rail adapter. (-->MLOK is -∆5 oz lighter than picatinny version)
Atlas is not QR, to get this...CAL NC is $240 x13oz with no mount, adding RRS QR is 2oz and $80, plus the weight of the pIC rail itself (2-3oz)=17-18oz total system (~500g, $320 total)
Sako style bipod is inherently more stable, but the legs etc need to have more material since they apex above the barrel, not below the stock/chassis forearm/etc. The Atlas is same technolgy as Harris style in terms of how the weapon sits on it like an A-frame not under it like the SAKO.
There are tradeoffs involved, the sako is more expensive usually harder to OEM
Sako-style bipods
Valhalla - MLOK 400g $500--ish
Elite IRON - 675g $700?-ish
Sako Bipod - 750g (for reference) $500-ish
Harris style bipods
Atlas CAL+ QR - 500g -- $320
Spartan's website says the Valhalla was designed from input by hunters and military. Honestly, it doesn't matter if they are targeting .mil or hunters or PRS or airsoft - the specs/functionality speaks for itself.
Spartan's whole niche is "lightweight". The Valhalla is 13 oz, a pic adapter is 3.9 oz, and an M-Lok adapter is 1.3 oz. At least half of Spartan's marketing is showing the use of the pic rail. Regardless, the lightest configuration per Spartan's website is 14.3 oz for the Valhalla using the M-Lok adapter.
The 2-screw (pic mount) gen2 CAL is 12.87 oz, the QR pic mount CAL is 14.57 oz, and the No Clamp is 12.65 oz. An atlas M-Lok adapter is $30 and weighs 1.135 oz. As you mentioned, RRS/Gray Ops/ADM also have additional mounting clamps that generally weigh a couple ounces and cost somewhere in the $70 - $125 range.
So in terms of weight, you might be able to save an ounce going with the Valhalla, and that's being very generous and likely comparing apples & oranges. In terms of cost, you could buy the no clamp atlas ($240), M-Lok attachment ($30), ADM quick mount for pic rail ($65), and an RRS pro clamp for arca/pic rail ($70), and you'd still be about 15% less than the Valhalla.
Pulling the legs off of the Valhalla is a gimmick, and attaching the tripod underneath the Valhalla is a gimmick. They both cant (Atlas has 30 degress, while valhalla lists 10 degrees either side with limit screw), both can lock cant, both have "quick adjust" leg notches, both can add leg extensions, atlas has more aftermarket clamp options, atlas has better leg angle (wider when taller equals more stability), atlas has more feet options, atlas is cheaper, and atlas is basically same weight (maybe a hair lighter)
If the Valhalla was priced competitively with the Atlas, then yeah it's another option. If the valhalla maintained it's price point and was able to be 4 or 6 oz lighter than the Atlas, then yeah it's another option. But the reality is you save no weight, you pay more, and there's really no increase in functionality/stability/etc. with the Valhalla, and arguably the Atlas has more options.