I am no expert, but I have two Corona Guilds, a D40CE and a D50. When I was in the market for a rosewood Dread in the early 2000s, it was a no-brainer for me, as I have always appreciated the Guild mojo. I bought the D50 as a factory second off ebay, sight and sound unseen and unheard, for $700. It is a special one, and many have said so. No one has been able to find the reason it is a second. It even prompted a jamming buddy to buy a similar second, a few months later, off ebay. Unfortunately for my buddy, his does not play or sound as good as mine, especially unamplified. He still has it and gigs with it occasionally in a band. (He is a musician, I am not). The D55 has supposedly better wood grades and extra bling, top of the line. My D50 was so great, I bought the D40CE about a year later. It is nice but not special like that first D50 that I totally lucked into. As an aside, the bridge did lift on the D50, but I left it out of the case now and then so it probably dried out a bit at times (never again!), and it is a guitar for which a $200 repair cost for ten years of stellar service is nothing.
Most importantly, you said the D55 plays and sounds good, and you like the sound and feel. Seems like you stumbled onto one like my D50. I am not sure what “varnish peel” means, or if your D55 is in otherwise excellent condition, or New Old Stock. Regardless, if you are buying to play (Guilds are made to be played!), and you can live with the cosmetic issues, then I would say $800 is a real bargain, but again, I am no expert. Good luck with your decision. Dave