I asked APB about this a couple of years ago, pointing to the reduced crosswind limits for 737s with winglets. Their answer was
“The FAA will only let us document the max winds experienced during flight test... so if we had been able to find more crosswind, then the 33kts might have been more. There appears to be no weather cocking effect due to winglets.”
Personally I am not convinced. The winglets must give a weather-cocking effect ie increased directional stability / reduced directional controllability hence the reduced crosswind capability.
Re “sluggish roll control” this has been noticed by NG crews who operate mixed winglet & non-winglet aircraft. I don’t know if the NG has the extra VG’s. The initial force to induce a roll will have to be increased because of the extra weight at the wingtips. This could be interpreted as a reduced roll rate by someone not used to such analyses, although the steady state roll rate (roll rate once started) would be the same. Whether the 235kg has this much effect with hydraulic controls I am not sure, I have not flown one in manual reversion yet but I would be really interested to hear from anybody who has.