Thanks! You're right about the Marathons, I did think about trying different tyres (maybe Duranos?) but will probably move it on and focus on the other projects.
I don't think I've used Duranos so can't comment! I ended up with some 700x38c Terravail Ramparts on mine and they're brilliant. I've moved them over to the replacement now. Not cheap though so maybe not worth the investment if the bike isn't doing anything for you.
Thanks! You're right about the Marathons, I did think about trying different tyres (maybe Duranos?) but will probably move it on and focus on the other projects.