Eugene van der Pijll
It looks like the Mayfair edition is based on the v3/retuned rules, with some additional changes. Is that right?
Is it worth trying the v2/original rules with the mayfair edition, instead (or even possible)? What would be the main difference?
Probably not. The v3 rules here on BGG contain an appendix with the things that are changed in these rules, and the rationale for doing so. They appear not to have changed the spirit of the game, but claim to have prevented some abuses of the rules.
Are there other/alternate recommendations to make the mayfair game less boring?
I don't know. Probably the best is to change your expectations; this is a fine game for engineers, and the main skill tested is to build good networks. There is little or no possibility for financial trickery.