Congrats on the 100+ activations Carolyn.
On occasion that I have got to use an FT-857, I have never really liked it, and always felt more ‘comfortable’ going back to my 817. My 897 at home seems very similar to the 817 to operate, so I do like that too, although too bulky for SOTA despite it being marketed as a “trans-portable”.
I don’t think any of this is to do with pros-cons of each model, just my personal taste and embedded operating style.
I think HF SSB really benefits from the extra power, especially on 40m. We have only really done well on 40m SSB with 5 watts from Northern Scotland, or near the South Coast of England. 80m SSB with 5 watts is normally reliable in winter, or early mornings. 20m SSB is sometimes exceptional good, and sometimes difficult! CW is easy on all bands at (nearly) all times with 5 watts.
I haven’t yet properly counted up how many (on average 1 hour) activations I get out of my 7Ah SLAB, while operating 5w CW from the 817. It is quite a lot! I don’t use an amp.
Steve G1INK would be a good person to ask about the power consumption where FT-857 running some power and SLABs are concerned, because that is Steve’s usual MO and he gets great results.