In brand re-positioning, with all things being equal, do you think it is important to separate the man/woman (client) from the brand?

Well, if the gender differentiation works for the product line and usage, then definitely its a path to take. Doing a seggregation just for the heck of it, is not worth it else we end up effectively is shutting of other half of the market! 

Demographics and gender roles have greater impact on buying patterns. One need to analyse its product and customer buying patterns before finalizing brand strategy.

I am no repositioning expert but I would not separate the clients from the re-positioning process, as one needs continuous feedback from clients (actual or potential) in order to decide how one should reposition your brand and then to evaluate if that repositioning strategy is producing the desired effects.If one assumes that brand repositioning is made in order to change customer perception (and, hence, customer reaction) to a certain brand, then how to decide the repositioning strategy and evaluate if the desired effects were achieved without client input?

It is wise to gender segment while you are re-positioning a brand if the product/services associate with the brand (or products/services in the pipelines) are gender specific.