There is no end to this discussion. Some will swear the 1000 is the only reasonable choice but others will say the same about the 650. Only the rider can make this call. Before buying my first Wee (2005) I spoke with two guys I ran into out in Death Valley, one on a 1,000 and the other the 650. They were buddies and had traded bikes back and forth so each was well aware of the attributes of both machines. Their answer was "Both were great bikes, each with its own advantages".
I have never ridden a 1,000 but I did spend a lot of years with my Triumph 1050 Tiger. I know what a 1,000 cc bike is like. After trading in my 2005 Wee on a 2017 DL650 I sold the Triumph. It was in perfect condition but I just didn't ride it any more. It had wonderful suspension, a beautiful 1050cc engine that would pull your eyeballs back into head, and so much more. But, all my ridding time was being spent on the DL650, including two-up with my gal. (wife actually). We saw no further reason to keep the mighty Triumph, the Wee was all we could make good use of.
1,000 or 650? There is no wrong answer. Both are great, just get the one YOU feel is best for you.
'17 DL 650 Vstrom, Best value ride of all time. (replaced our '05 Wee)
'07 Triumph Tiger 1050 Feel the Power! Culled from the herd...gone but never forgotten.
BMW K1200 GT, Gone but never forgotten
BMW K100 RS, Beautiful German engineering
Husky 250WR, (1986) Last of the real Huskies made in Sweden
Bultaco's ...for those of you who remember....
A long list of so many others.....
Happiness is having a motorcycle with more power than you will ever need.