Do you have rim tape to protect the tubes from the ends of the spokes?
I've previously ridden on Marathon Plus' without incident (700 x25), Switched to Vittoria Randonneur 700x28 as I wanted a cushier ride and couldn't justify the $30 price difference in my own mind
No issues in first 100km this week.
Remember tyres come in different widths. Most ride on 700x25 or 700x28 for commuting.\
To complicate things, look at the TPI (thread per inch) - I get confused. I think the more threads per inch then the stronger the tyre.
- but someone can correct me if I'm wrong.
If you are really interested there is a youtube clip on how Marathon Plus tyres are manufactured.