do you like the bucket seat ?  test paddle a boat with a bucket seat before you make that decision.  

as far as whether a sliding seat is better, that's just personal preference.  it is obviously easier to shift your body weight to adjust trim with a slider, but I've never felt I needed or wanted one - I have no problems just shifting packs to do the same thing.

Wenonah offers some kind of height and angle adjustable bench seat, but that does not appear to be a slider? nor offered for the encounter? but maybe it is - I'd ask the dealer about it - they may have one you can look at - not sure if they are sized to fit the encounter, but it could be cut down to fit I think.

I used to have a link for a slliding cane bench seat, but it won't work anymore - you might be able to find one if you wanted to change your seat in the future