Just my .02¢ on comaprisons/similarities between guitars and some things about blades I have seen discussed here:
1. Coatings. I have seen some discussion on blades changing with the wearing off of the coatings used. I have seen
RayClem mention some blades may get sharper as the coating wears off. A lot of guitarists believe the sound/tone of guitar strings can change as the coating wears off. No one wants old, dirty strings, but some will change strings before a gig or recording to make sure the strings are "broken in". That meaning they are stretched a bit so they hold better tune, and some believe it takes the edge or bite off the strings when they are new. Some believe they sound harsher or at least the highs do.
2. Production year. I just happened to see this mentioned on Wizamet blades as well as others. And some razors also like the Muhle R41. Owning many guitars, having sold them for close to 17 years, and having many friend enthusiast/collector/players, I have heard the talk/debate over production years. Don't buy this year, buy this one. Specifically Gibson guitars because I own a few and know many collectors. They seem to have had periods of production that collectors and some players prefer to avoid. I do remember one production year as I was selling that was particularly not the best and I wouldn't buy one. A lot of people were bringing in new guitars for basic work that should never have been needed buy a guitar at that price point. Workmanship and finishes were poor and it was well known.
So, those is just my thoughts on some separate hobby similarities. And yes. Just as you need that razor in copper, stainless, and aluminum, you need that same guitar in blue, red, and black.
integritas pietas fortitudinem