Scott,
I cannot argue the relative merits of the 800 series. I can tell you I dont agree with your sentiments.
I didnt know the new players dont upsample CDs inside them- this seems strange. A quick look at the specs on the player shows this to be correct. I suppose they want some area of differentation to the 800.
I do agree that the 5 series you have seem to work as a pair and I agree its best to not split them up.
I can tell you that a while ago someone said to me that B&K gets 90% right, but its the 10% they dont get right that really kills their products. Let me put it to you this way- if their products were that good, I wouldnt have upgraded to Lexicon. And if their products were so good, I wouldnt have upgraded to Meridian. I have been completely satisfied with my M gear- Ive just followed the upgrades.
As to Lexicon- getting the MC-8 puts you somewhere performance wise on movies on the level of the 5 series you now have. Do you really want to go through this trouble to be at basically the same place, but with worse music performance?
If my options were to cash out and then get a Lexicon or B&K piece- in your place I would pass on the deal.
As far as what player to get- I would get a player that doesnt cost more then 500- probably a panasonic, but I would check with the Secrets list that it does not have the color upsampling error, there would be no need to do anything more.