Do what makes you happy. Yes, there will be metallic particles in the oil at 400 miles. And in the Diff oil too. Enough to make a significant difference over the life of the vehicle? I guess a lot depends on how you ride and how long you plan on keeping the bike. Yes, the exhaust waste gases are in the oil and will combine with the moisture to form acids that can etch internal engine surfaces over time. Over the winter? I don't have a clue. Nearly any reputable source will suggest you store a vehicle with clean oil for best results. The length of storage and conditions make it highly variable. Heated garage, probably a little less of an issue. Outside in a shed or under a tarp, likely more chance of negative things happening over the winter.
Regardless, I'm a fan of overkill.
Hardly ever has clean oil hurt anything. Probably a tiny margin of people adding Stabil or similar to the gas ever had a negative issue. The number of people suffering complications from having a bike battery on a
maintenance charger are likely pretty slim. Especially a good quality one like an Optimate.
It's your new toy. splurge and change the oil in the engine and diff. Try and fill it up with non-ethanol gas first and go for a short ride to get it into the fuel system. Toss some fuel stabilizer in there when you fill it up and invest in a good maintenance charger that can safely be left plugged into the battery w/o fear of overcharging. Come Spring, you'll be able to just un-hook the bike, roll it into the sunshine and fire it up.
Don't be tempted to fire it up every now and then in the garage. Don't fire it up at all if you're not going to go for a ride and fully warm the bike up. Avoiding the short engine run will mean you avoid the hard start issue later too.
