some questions about wetsuits (soon to buy first wetsuit need advice)

is there anyone that wears a 7mm FJ?  And if so, what is the comfort level during summer?  Winter?
i was talking to Bajareefer, who wears a 7mm, and he's very comfortable in it.  If i am in a rescue situation and in the water for a few hours, is the 3mm suit going to be sufficient?  I'm leaning towards a 7mm, as i also plan on diving for abalone.  Can buy a separate suit if I have to.  Would appreciate further comments. 

Over time, I have evolved my own practices as follows....

Diving;
I found a happy medium in the Tilos ultra stretch full suit. Its 7mm but a soft and very flexible 7mm.
 On abalone and spearfishing kayak outings, I roll it down past the arms for free and easy paddling...When arriving at the dive site...just roll it back up.

Fishing;
The farmer john I wear for fishing is a 7mm henderson hyperstretch w/ no constriction around the arms at all.
This rather cold summer is almost over and only on one day did I have to pour water over my head and suit to cool off.
I wear 7mm booties always and go out on the assumption that if I'm gonna get dumped....I'll be floating, swimming easily, unfrozen and fine.
 True, a farmer john is not warm at the shoulders but at some point you will be getting out of the water hopefully.
If not, hard swimming towards shore or another craft warms you up a lot more then floating in place.
But, compared to a 3mm and a PFD ...the 7mm keeps you a lot warmer [and bouyant] then anything else.

The full Tilos however makes one laugh at the idea of getting wet , cold, drowned etc,
Steve