Get a big tank & enjoy yourself. Your SAC will likely come down with experience, but that's going to take time, who wants their dives cut short in the meantime, and if you later 'don't really need it,' gee, you'll have a lot of extra gas on your dives in case you or a dive buddy needs it (e.g.: in an emergency).
On the issue of 'gear solution to a skills problem,' I see that come up on a number of these threads on the forum. And the common scenario is this:
1.) Diver is a MAN.
2.) Diver is often fairly large. Maybe not always, but commonly.
3.) Diver may be fairly new, or even moderately experienced.
4.) Diver is often discouraged from getting a big tank (e.g.: like my HP 130).
Now, here's the funny thing. I've yet to see a petite female fresh out of OW with the same level of competence, but blessed with a naturally low SAC, told she shouldn't be diving an 80 cf tank because that's a gear solution to a skills problem, and she should dive a 63 cf tank & work on getting her SAC down a good deal further because otherwise her dive times are too short.
What is the difference?
The only difference I see is that for vacation diving, 80 cf tanks are the most commonly offered, and it's good to have familiarity with them if that's all that's offered where you're going to go.
For local diving, I dive an HP 130 steel. In Cozumel, I went with Living Underwater, which provided 120 cf steel tanks. In Bonaire, St. Thomas & other Caribbean locations I've dove, I made do with the 80 cf aluminum tanks that were on hand.
Richard.
