I have never used the Marathon Plus but I did my research about puncture resistant tyres a few months ago and the Marathon Plus were the tyres to go for...... I decided against them for the simple reason they were too heavy for the bike and the type of riding I do with that particular bike. I think Marathon Plus has a sister tyre that also has the same puncture resistant properties but lighter and of course, more expensive
Also, my research revealed that the Marathon Plus wears quicker than the average tyre but it's excellent otherwise.
There is an Armadillo tyre (not sure of the name) that is worth considering
I went for Gatorskin and so far no punctures........