If “doable” is the measure to be considered here rather than practical, enjoyable, better than other alternatives, less expensive, I agree with you. It is doable. It is even more doable if the commute is principally on LA freeways, which are relatively well paved and on which lane splitting over wide lanes is legal. None of the above is applicable to NYC highways and streets. Putting aside the condition of the pavement in NYC, lanes and spaces here are too narrow for a K1600 to fit for lane splitting when traffic is stopped. And, in any case, lane splitting is illegal.
To put things in perspective, a 50 mile commute half on suburban roads and half in NYC on an R1200R during rush hour (which starts at 6:00am and ends at 9:00pm) with lane splitting albeit illegal lane splitting takes somewhere between 45 minutes to an hour, while the same trip Ridden by the same rider takes no less than 1hour, 30 minutes on a K1600 GT. The seat and electronics on the K certainly make for a more comfortable ride, provided that you enjoy sitting for long periods over long stretches of road in barely moving traffic, with fumes from the cars and trucks surrounding you wafting through your helmet and time is not a consideration
I don’t and, I expect, most riders don’t either. So, like I said, whether commuting on a K1600 is a good idea depends on the circumstances of one’s commute.
THIS^^^^^ is it.
Everyone's circumstances and priorities are different. Just speaking for myself, if commuting meant just in-city, stoplight traffic, no way I'd do it regularly on a K16. But if you have a long commute, the in-city tradeoff might very well be worth it, with the increased luggage capacity to stop by the grocery store for something more than ham and bread, and relax on the freeway.
As others mention, are you gonna lane split or not? Narrow profile is an absolute must there.
How heavy is heavy to me? Can I relaxed flat-foot at every redlight, or will I be up, standing on the balls of my feet? Usually, that should make no difference, other than subjective preference, in deciding on a bike to buy, but if the bike is especially heavy, AND you have to just LIVE amongst congested traffic with stoplights, the ability to sit there like you're on a Barkalounger won't tire you out as quickly.
Do I have a second, lighter-weight bike that could pull commuting duty easily, if I don't have a long commute and can do the backpack thing?
already has one, the Bonnie, so I'll ask this question, since this seems obvious: Why can you not commute on the Bonnie in the summer and the K16 in the winter? That's what I'd do where you are, and seems like a perfect solution.
Lots of folks can give you things to think about, or examples, but as a friend of mine says, "You gotta do you."