Wow, your minor problem is really well looked after by everyone.
I'd say if you will ride in some seriously wet/snowy weather and want the pedal to be problem and maintenance free for a long time, get sealed cartridge bearing stuff, but pay the price difference in cash to the shop. They are a lot more expensive then the cheapo plastic crap that broke on you, and the shop has no reason to lose that money.
Don't know the MKS, but if it is "track", it's probably not sealed, as it seldom rains in indoor velodromes. (Loose ball bearings are not a problem inherently, they can be sealed reasonably well)