The chicanes on the Mulsanne were put in following a crash of the TWR Jag XK-8R in (I think) 1988 or 89. Another one was added in 96 following another crash which was fatal (steering failure, and the car lifted off the track).

No idea about the comparison: probably faster in a straight line, but I doubt they would corner as well as the modern chassis. I thought the Merc was the one that took over from the 917?