I have a pair of the 12" Omega Subs.
Yes, they may a considerable difference for the better; easily heard and appreciated.
The question I cannot answer is, does two 8"s better one 12".
Based on my personal experience, two 8"s are dramatically better then one 8"
This I have heard for myself, and have other people tell me the same.
Perhaps if you PM me, we can discuss this at length.