In reply to MM0FMF:
One person who can give more info on the choice is Gerald G4OIG who predominantly uses VHF/UHF and has both an 857 and lightweight battery pack and an 817 + VHF/UHF PAs plus batteries.
Basically it comes down to “horses for courses”. I am currently using the 817 + 2m 25W linear combination as I am activating the GM/SS summits. The advantage of this system over the 857 is one of battery drain. The 857 (and I assume the 897 also) takes significantly more current than the 817 on receive. Also I get the benefit of the preamp in the 2m linear module. All positive points for activating several summits that are relatively remote from the core of the chasers.
Now for an HF only activation, I am getting to prefer the 857 as it has a higher output which is useful on SSB (I think Steve G1INK will agree on that) or when conditions are poor. On CW, an 817 is usually sufficient provided you get spotted.
I wholly agree Andy about the 817 being fiddly with gloves - in my opinion, it is nigh impossible, so I always abandon my gloves when it is cold to operate and then have great difficulty getting them back on when my hands are cold and damp. The 857 is much better to operate when wearing gloves.
As for batteries, the 857 requires a 4S LiPO plus diode dropper or as I have, a 3S LiPO and large capacity single cell NiMH in series to get the 12V nominal required. The 817 just runs off a 3S LiPO. When running the 817 + 2m linear combo, the 817 runs off the LiPO alone and linear runs off the LiPO + NiMH.
It really all comes down to personal preference. I think having one of each allows me a measure of flexibility… and as to weight, well the radio is only part of the total. If I was that worried about weight, I would probably risk not taking the first aid kit, the bothy bag, the plastic tarpaulin, etc.
73, Gerald G4OIG