Sure,
chi-sau is meant to be a stepping stone to translate your training into fighting ability, but if you want to test and compete against other styles it should be done in free sparring. I personally look upon other WCK lineages as other styles, because their thinking can be so vastly different to my own. So I
chi-sau within my lineage to develop skills used to face other styles in free fighting.
I will never understand why Wing Chun people get together and just want to play their favorite game of
chi-sau rather than spar. Having fun and being good in
chi-sau may be their ultimate training goal, but it's not mine.