Dear Bob,
Thanks for your answer. It definitely answered my question. Ya, I thought of it might not be advisable to do this because of the imbalanced performance; I've overlooked the capacity and rebuild risks.
Initially, I thought I've seen somewhere stated the hosts within the same VSAN cluster need to be the same configuration including the number of disk groups or disk slots but I couldn't find it.
In short, I will say it is a NO for this kind of configuration.
Thanks again.
Eddy