Well, I was kinda busting your chops man.
Personally, I think engraving is ugly. I suppose that puts me in a minority, but I much prefer clean smooth metal to swirls, and curliequees, and oak leaves. Never did understand the attraction.
Frankly, guns like yours and mine have almost no real "collector" value. They're what're called "shooters." A gun has to be in almost perfect condition to attract the attention of a serious collector, and there is a BIG difference between a 95% and a 98% gun. Ours aren't close to 95%.
So would you hurt the "collectors" value? Probably not, because there isn't much. Would you hurt the market value? Probably so. A refinish not at much so, but you wouldn't recover your investment. The same would apply to engraving, but more so. You get something like engraving (or refinishing) done, because you want it done. Not because you think it will add value.
What you've got is a great example of "the way they used to make 'em." Shoot it, enjoy it.
I am not an expert, and it's been a long time since I stayed in a Holiday Inn Express.