I'm with Paul. I can't think of a more uncomfortable tyre than the Marathon Plus (and its workalike, the Bontrager Elite Hardcase, whose name already tells you you need a bum of cast iron to ride on it). 99.9999 per cent puncture proof it surely is. But then so is the most comfortable tyre I know, the 60x622 Schwalbe Big Apple, a distant cousin of the Marathon, 99.9999 per cent puncture proof. I know which one I'd rather ride on.
Trivia: The Big Apple is supposedly part of the Marathon range, but I doubt the relationship is close enough to feature in the frontispiece of a Church of England Bible as forbidden consanguinity.
Come the the spring or the summer, you could experiment with lower pressures in the Marathon Plus and gain a margin of comfort.
I had a pair of Big Apple on my 26" bike, and punctured them both within a season. My wife (half my weight) now had those transferred to her 26" and she has had one puncture since- although they've been mounted for years as she is only an occasional 'pop down the shops or ride around the park with the kids' kind of gal!
I replaced the Big Apples with the same sized Marathon Plus on the 26", and have probably ridden around 2000km without incident since fitting.
To be honest, now you mention it, when I bought my 28" Winora with Rohloff, it had 32-622 Marathons on it, which I found very uncomfortable on anything other than smooth roads. But these were quite worn out, and the seller gave me a set of used 40-622 with reasonable wear still in them which were a big improvement in comfort, but still narrower than those 42-622 on my 28" derailleur bike.
I think there is much to be said for a wider tyre adding comfort. The German bike club ADFC have long recommended good balloon tyres as generally more comfortable (and far cheaper) than bikes with most entry/mid range suspension systems- and I have to say that my Winora Labrador with Suntour NCX suspension fork is not noticeably more comfortable than my similar sized derailleur bike on those slightly wider marathons. While a small statistical sample, I've not been convinced that the suspension fork is a must have if I were putting together a custom bike. Good tyre choice might not only save money but make more sense for longer term comfort riding.