Should I replace my 10000km Schwalbe Marathon Plus Tour with a 2000km Schwalbe Marathon Winter Plus? Background
I have one Schwalbe Marathin Winter Plus tire that is in good condition (used for 2000km, 10 months old). Below the winter tire with spikes removed.
 
On the bicycle at present is a Schwalbe Marathon Plus Tour (used for 10000km, 3 years old). Below the summer tire.
 
I am moving to a country where I will not need spiked tires. Because of weight limit I cannot take both tires with me.
I was thinking of replacing one summer tire with one winter tire. I normally only cycle on tar.
Arguments for replacing the summer tire

10000km old / 3 years old
1cm long gash on side of tire due to piece of glass. Gash narrows to a small hole where the tube is visible. I put a boot on the inside.
Winter tire only 2000km old / 10 months old and no gash

Arguments for not replacing the summer tire

Summer tire still &quot;looks good&quot;. Tread still looks deep. Tire not smooth. The blue of the inner layer is not showing.
From experience with Schwalbe Marathon tires, gash is not a problem (this is the 3rd large gash on 3rd pair of Schwalbe tires)
Concern: the holes for the spikes on the winter tire are prone to punctures ?
Concern: the rubber of the winter tire is different than the summer tire rubber. The winter tire will wear off faster ?
Concern: winter tire has more nobbles, i.e. the summer tire seems thicker

(Detail: Of course I also have a front winter tire. But the front winter tire has a large 2cm gash also caused by a piece of glas.)
I don't think the holes in the winter tyres will be prone to punctures without the spikes in them. They're a very small target. I have had damage from the inner end of the spikes themselves wearing through the belt on tarmac (occasionally icy).
These winter tyres aren't as tough as the marathon plus (tour) though, both in terms of overall puncture protection and wear - winter compounds are softer. They still probably have more life than marathon plus with 10000km on; at least at the back that's about how much I get.