Between 1050 and 1055: Aesthetically, everything... technically, i am not so sure.
There was a 1051 in between which combined the past and future somewhat awkwardly, in my opinion. Again aesthetics.
105 did go from 6 to 7 speeds in that time, but i think that was more of a shifter change than an rd change. But i always ran these in friction, so i can't say for sure.
According to Velobase '1050 is the first indexed 105 group', which was 6 speed.
After that, the numbering then went to 1051 and then 1055 (though the actual 1055/6 groupset seems to be known as 105SC, somewhat confusingly). I think...
It was when it went from a polished finish to painted, in the champagne colour, so maybe 'silver champagne'? That's just me guessing, though, I could be totally wrong...
Interesting...though I must admit I prefer the non painted finish of the 1050 to the painted 1055.
The 90s design and lettering on components was too 'blown' in my opinion...for what it's worth
Well, it is hard to beat a nice polished finish, I agree. I think the champagne colour is rather nice, but of course anything painted starts to show its age in time. When it went south looks-wise is the 105 5500 series from 1999 onwards, I'd say:
On the plus side it's a nice anodised finish, but the yellow and blue lettering...