Re the ultimate advice we want to give to the original poster I disagree with you both, but since most of the things you say are correct let me explain myself with some concrete observations from my experience:
a) It seemed to me that the original poster wanted to avoid lots of theory & maintenance for reasons not given to us (e.g. lack of time to study? other heavily theoretical lines already in the repertoire? etc.). Otherwise, Lou_Cyber has a point indeed. So, Chessmoby please enlighten us on how strict you are on that.
b) From a Black's player point of view, 6. Bg5 is the most dangerous line to face (followed by either 6. Bc4 or 6. Be3 & f3). But White has to do most of the preparation (not Black!) as he has to face many heavily theoretical lines (PP, Classical, R.Rauzer-style, Polu, quick Nbd7) that also lead to positions that are difficult to assess as a human (hint: you'll frequently need to perform some computer analysis). All Black has to do is to book up in one particular response and he/she's almost certain to get it game after game. E.g. I use a decent sideline in the Classical variation (6. Bg5 e6) and my opponents often spend 30' on the clock just to play their first 5 moves after we enter this sideline.
c) Following a comment by Lou_Cyber that the player with the Black pieces apart from the theory to cope has to defend as well: Maybe true for the PP, but e.g. in the Classical lines against 6. Bg5, Black usually counterattacks (a la Dragon).
d) 6. Bg5 e6 could easily become an e5-type of position later on in the game, so a good positional feeling for these positions is still essential.
e) imo theory is not that huge after 6. Be2. You can play it for many years just knowing a couple of the main lines and all the thematic plans. It is mainly a positional struggle. On the contrary 6. Bg5 positions can become very counter-intuitive and you'll need to do some memorisation from day one. So I see a big difference here; but it's ultimately a decision based on taste or style.
f) And a last note: whatever you decide I recommend you follow the same plan against the Classical Sicilian (Nc6) due to the high possibility of transpositions (e.g. Be2 against both or Bc4 against both or Bg5 against both etc.).
chk