iamcanjim,

I agree with you, on most points!

They are all based on Honda CMX250 Rebels, specifically the Japanese Domestic Market edition. Therefore, unlike US Rebels, they have twin carbs and the disk brake is on the right on the single disk models.
Correct! Unless they are the Regal Raptor road bikes, in which case they are based on CB250Ns, with some home grown technology inspired by later Hondas such as CB400 or Hornets.

As you go along the line, various mods have been made to the original design. Water cooling, boring the engine out ot 300 or 350 cc's, etc.
Maybe, but there were some original Honda 350 twins (320cc), many years ago. Could be simply bored out 250's though, not sure. Water cooling is fairly orginal with these engines though.

my suggestion would be to try sitting on a DD250E, the air cooled basic Honda Rebel clone. Simpler (so less to go wrong) and the frame and chassis are definitely properly engineered. My Rebel easily hits 120 km/h, so it is certainly fast enough. Having ridden the water cooled 250, I found the increased mass and complexity did not make up for the slightly increased power
Possibly, my suggestion would be that Regal Raptor engines are inferior to the Jialing/Honda engine in your bike (when new), and ideally need at least oil cooling to give optimum power in hot weather. But water cooling may be too much weight, agreed.

The Spyder is probably too raked out to be able to avoid brain dead Chinese pedestrians.
So true!

Finally, the monoshock RR's just plain don't seem to have the rear shocks to deal with the weight 2 up.
Very true, disk brakes and a monoshock may seem ideal, but in reality it really depends on the quality of the parts used, much less than what 'it is' in theory. But the twin shocks aren't that wonderful either!

So, in short, I think you should consider forgoing the water cooled 350 engine for the aircooled 250 and should forgo the spyder for the twin shock 'chopper.' This is based on riding my rebel and trying a water cooled chopper.
If he was able to test ride the Daytona, Spyder, and 'chopper', for at least 10 kms each, I'm sure would be able to make a good judgment about which bike is right for him, sadly, this is China and this may prove impossible .