They're much more comfortable and quieter than the 125's (43's + mk3s) plus they don't give you a face full of fumes when they start up or scare your children :)
In all honesty I prefer the HST125. Part of that is nostalgia, the HST125 is a great example of technology from the golden age of British Engineering which, like the Route-master bus, outlived several generations of successors. The other part is the Voyager fleet in my experience always smell of toilet.
I was fortunate to be working in the centre of Newcastle around 2007 when the last of the Valenta-engined 125s were in service, and I'd hear the north-bound trains pulling out of the station. But since then they've changed to newer diesel engines, and they don't have that glorious screaming turbocharger anymore.
Yeah, I know that sound well. It's a sound I strongly associate with Edinburgh train-station having taken the final leg of the Kings-cross service back to Glasgow many times while at University.
Apparently the sound of the Valenta engine was used a clip in a song but I've never figured out which one.
http://en.m.wikipedia.org/wiki/Bombardier_Voyager_family
They're much more comfortable and quieter than the 125's (43's + mk3s) plus they don't give you a face full of fumes when they start up or scare your children :)