I won't be able to tell you if it is worth it to credit your flying to AV but will add: 1/ you need 15k miles on AV metal to qualify for their top tier.
2/ If you plan on using your miles to fly AV: go for it, if not I'm not so sure I'd do it.
3/ With LifeMiles you can always buy miles and sometimes thats a more interesting strategy.
4/(the most important to me) If you plan on flying regularly on AV metal being silver, gold or diamond gives you unlimited space based upgrades on all but flights to Europe, thats the perk that makes the whole thing worth it for me (as a diamond I rarely ever fly Y on AV).