Winter tyres or winter wheels?

I'm assuming you have rim brakes, since you are asking about wear and aligning brakes.

• Winter riding will wear out everything faster. The rims are going to be wet and dirty for most of the time, and the same goes for transmission. It might be a good idea to use any old equipment you don't care about as winter parts. The exception is that better hubs have better sealing. 5000 km isn't that much for rims, by the way.

• Unless the rims are exact same width (or the rotor is aligned exactly the same) you'll have to adjust brakes every time you switch wheels. Possibly the derailleur too.

• New cassette on worn chain will be noisy, wear out the cassette fast and skip if the chain is worn badly enough.

One of the advantages of having winter wheels is that you can spec wider rims for the winter season. Fatter tires should be able to give you more traction in snow and mud. You can then switch to thinner rims and tires in the spring.

Your winter wheelset could be on the cheapside since you're not particularly interested in superlight wheels. You can often find very cheap used wheelsets on craigslist from thieves who steal wheels people upgrading to lighter wheelsets (if you buy the used as a pair, you lower the risk of buying hot goods).

But yes, you'll have to realign your brakes if your rim width changes or if you switch wheel brand/makes. But that's a relatively simple job - as is adjusting your derailleur (which might again happen unless you use the same brand/make rear hub).

You might as well have a dedicated winter chain to go with your winter rear tire/cluster -- or just replace your chain every spring. This'll prevent the excess wear on your winter chain from affecting your summer cluster too much.

Offering a compromise solution:

I had a spare front wheel with a studded tire when I was broke and biking all winter (on a cheap 26" rigid MTB)

I still haven't run full studs four winters in to bike commuting in the upper midwest.

One thing to consider is the effort to install a tire to the rim. Summer tires are thin and supple, so the effort to install a tire is minimal (unless the rim is a "tubeless compatible" rim in which case the effort can be Herculean).

However, studded winter tires can be bit stiff, so you may not be able to install a tire in less than 5 minutes. For example a 10 minute job would mean you need to do the job to four tires per year, wasting 40 minutes per year. Over a period of 10 years, this would waste nearly 7 hours. Depending on the value of your time, this may make having a second wheelset more alluring.

Also you have to consider what to do when a wheel fails. Unless you're an experienced wheelbuilder and have a truing stand, wheel failure usually is slow to be fixed. A second wheelset will allow you to continue riding when the broken wheel is being fixed.

A second wheelset also makes it more alluring to change wheels due to changing conditions. For example if studded tires drop your average speed from 20 km/h to 18 km/h, then a 40 km ride would equal 13 minutes of time lost if unnecessarily using studded tires. I'd say you can swap the wheels in 13 minutes. Even two or three non-snowy/icy consecutive days during winter would mean you save a lot of time if you have the ability to quickly swap the wheels.

Furthermore, do consider that areas with real winter usually use sharp gravel to prevent pedestrians slipping and falling on ice. Many areas erroneously place both pedestrians and cyclists into mixed use paths, meaning the cyclist also has to ride on the sharp gravel. This sharp gravel tends to puncture bicycle tires, so some solution to prevent punctures is needed. A good solution is Tannus armor with some increase of rolling resistance. However, installing the armor is a Herculean effort, for me it took about 40 minutes per tire. So that's 80 minutes of time lost every time you put the studded tires to the wheels. I don't know how hard the armor is to remove but if removal is significantly easier than installation, in 10 years the difficulty of installing the armor wastes 13 hours of your time. I'd say using this armor is a very good reason to have a second wheelset as its installation is so hard.