Sophocleese, this phrase of yours is a pleasure for me: "I personally prefer singers who have clearly thought a lot about their singing and invested the same amount of time learning to sing as they would learning any other instrument."
I'll never regret to have invested a lot of time and money in studying vocal technique, and will always repeat to beginnners that there's a whole universe of difference between STUDYING and NOT STUDYING with a good, classic teacher, doesn't matter wether you are facing a popular or classical career. There are lots of good voices ruined by singing out of their natural range, full of vicious habits, of people convinced that a rusty emission is good for their repertoire, or a weak one is more expressive.
Un abrazo - Andrés (a bass who happened to be a baritone and later a tenor)