Anyone in Reno NV with a 400 Burger?

what are your concerns , needs, capabilities, we might be able to help you decide without having to ride, there are fewer differences between the 650 and the 400 than there are between different year / models of the 650, the 400 stayed pretty standard after 2008 except it lost some trunk space, there is less maintenance on the 650 but the 400 performs just as well except for super slab long distance stuff, where the heavier 650 feels more solidly connected to the road, the 400 is better for short trips like 200 miles and way better in town and in the garage pushing it around all the empty refreshing beverage recycle bags, Cost is obviously different, and availability too, What I'm tryin to say is , match the bike to what you will use it for , not for the ride, cause there ain't that much difference ergonomically and it's a burgman, not a hayabusa, so performance off the line is ALWAYS gonna be lacking, getting up to speed after you start is a different matter, but about the same on both bikes.
Welcome to the forum. we got lotsa experts here who can help with just about anything burgman related, and I can help with wine wimmin and song

Started out on a 2004 Burgman 400 and it handled my first 1500 mile (round trip - mostly superslab riding) with no issues. In fact, it exceeded my expectations and I was pretty impressed with how it performed for a thumper.

After a few years, I wanted a little more performance umph so I bought a 2005 Honda Silverwing. IMO, the SWing fits somewhere between the 400 and 650 Burgmans (yes I have ridden and am familiar with the 650's). The SWing's got plenty of power, lots of storage space and functionality without the Burgman 650's heft and girth which does suit longer, superslab riding.

I've been very happy with my choice. I am a taller, strong person and the SWing is plenty flickable enough for city riding and the twisties yet solid enough for superslab and secondary road cruising. Ergonomically, it is less comfortable, FOR ME, than our 2016 Burgman 400 is. The AN400 fits me like a glove and I really feel I'm "in it" vs, "on it" like I do with the SWing which even has a Corbin seat (doesn't help the seating ergonomics much for me) and that is my biggest comfort complaint.

For the record, I do about 50% urban, 45% secondary rural roads and 5% superslab roads plus the occasional gravel road.

I can't speak to the 650 but as a rider of 40 years and numerous bikes in my garage, the 400 is just so darn fun to ride and impresses me every time I ride it. Other than 0-10 mph, it's really almost no different than how I ride my other bikes. Sure, the bikes can accelerate faster if I pin the throttle, but I really don't do that much anymore. The 400 is completely satisfying to ride. I did add a $28 windshield extender (Amazon) which helped enormously with the OEM shield. So glad I did that. If you're tall then I'd recommend it. The OEM blasted my upper body and helmet (I'm 6'1") and the screen wobbled like crazy at highway speeds. The extender moves the air over my head and stabilizes the screen perfectly. It's also adjustable for times like summer where you might want a little more air.