The top tube is 1 1/8 th so I guess early 90s? Not sure of Columbus timeline.
I built with 105 group because it's a mid-range frame and I felt it was correct for the look / period, very happy so far.
Some of the RS 'failures' were in fact lacquer cracks around the BB , but I have a mate who is on his 3rd frame
The Cervelo is supremely comfortable, I did 40 miles to the first stop on one sportive and realised I hadn't shifted my position once ( or maybe it was the cold! )
I ride the steelies most of the time, they just have so much character, the Bertin ( up for a vote in BOTM ) is the most comfortable tho i can't really say why, it's just a sweet frame, but I'm gonna need a bit of help on climbs with 52/42 at the front and 13-19 at the back!
I suppose the short answer is the Cervelo for sportives and group rides and the steelies for a leisure ride with a couple of mates; I actually enjoy fewer gears, much more relaxing and unfussed way of getting around.