Maximizing profit. 6-max or full ring? 4-tables, 8? Several ?'s

I switched to NL recently. I played ~10k hands of 25NL full ring before switching over and playing ~30k hands of 6-max. I'm comfortable with both but found myself bored to death with 4-tabling full ring. If I switched back to full ring, I would want to work my way up to 8-tables ASAP. For those of you who 8-table, do you see much of a drop in winrate? I 8-tabled limit for awhile so I know to expect some, but just how much in NL? Nutpeddling/set farming 8-tables of full ring is profitable up to what limit? Is 8-tabling full ring at lower limits just a silly idea? Should I just stick to 6-max? Bankroll is not an issue, should I be looking to play 25k hands or so at NL50 and moving up to NL100 if things go well?

Here's where I'm at and why I'm asking these questions. I am going to do one of three things in the next week or so:
1. Start 4-tabling NL50 6-max
2. Try to get comfortable 8-tabling full ring at the NL25 before I move up to NL50
3. Move up to 4-tabling 50NL full ring and start adding tables there
(This is all assuming that hardly anyone plays more than 4 tables of 6max. Am I wrong?)

With rakeback, which of these options is going to be more immediately profitable? I am not just in it for the money, but while I learn NL and begin my journey upwards, I wouldn't mine making some. [img]/images/graemlins/grin.gif[/img]

I will be playing at least some of both 6max and full ring at each limit as I move up. I would like to know which should be my focus for profit and which for becoming a better poker player.