It's probably no longer relevant, as you pointed out, mostly due to technological differences. Technology has really become a decisive factor as it contributes to better firepower, intelligence, logistics, communications, command and of course defense! Geography, training/experience and resource superiority are also important variables.
But again, no, I don't think the 3-1/1-3 thing is relevant anymore. It's more like 'who's gotten faster chip' nowadays.
Look at Israel, for example. Israelis are vastly outnumbered and geographically surrounded by Arabs, who has more natural resources too but yet in a war --and I mean no offense to the Arabs-- Israel can (and have indeed) still own them hands down! That speaks volumes about how important the technological edge really is.