Howdy! I still have both and love both. This is partly because they're both great bikes and partly because I don't really have any more $$$ to buy or trade anything else. Fortunately, my current "stable" is more than adequate for my needs.
Weather protection on both bikes is excellent, particularly after I replaced the wind deflector on the BV500 with a full Givi windshield.
I see the SWing as the "mule", the machine I use to tour and run long distances. It's highly reliable, has lots of storage space, good power and handles reasonably well. It averages about 50 mpg. Service points are pretty easy to get to and the factory service manual is good-even if I choose not to do the work, at least I can see clearly what has to be done.
I see the BV500 as the bike of choice for day rides and twisties. The BV500 is also reliable, though I initially had some issues regarding the speedometer and it was then I discovered that the Piaggio parts pipeline, at least here, is, shall we say, leisurely at best, despite the fact that my dealer is a major BMW/Triumph/Ducati/Vespa/Piaggio dealer about 5 miles from my house. That said, the BV500 continues to outhandle the SWing due to the lighter weight, weight distribution and larger wheels and is truly a joy to ride. It has reasonably good power, although nowhere near that of the SWing...I suspect that the new BV350's engine might be close in power output to the BV500 and probably much smoother. Storage is much less than the SWing under the seat, although front storage is much better. If I need to carry more, I put on the smaller Givi box. Fuel mileage is 55-60, which is fortunate because the fuel tank is pretty small...I made about 130 miles on the tank going over Carson Pass awhile back and so I think it's OK.
So, I love them both and will keep them both. Every time I think about replacing one or the other with something else, I just can't bring myself to do it...they're both such good machines and have pleased me very much.
Here are some recent photos of the BV500 on a short run into Amador County and back out through El Dorado County via the Shenandoah Valley, a big wine vineyard region east of Sacramento.