I think you might want to consider leverage when deciding whether to strap gear to the outside, as well as whether you're exposing it to damage from rocks or brush.

Since there's no damaging a Garcia can (and I'd definitely rethink carrying one of those monstrosities--get a Bearikade or Bear Vault instead) you can focus on where you'd strap it. The ony place (IMHO) is on top, which requires a pack with an extendable top pocket or top strap anchors--very strong ones.

Strapped to the back or bottom, a full canister will unbalance the load terribly, more so on back. As we know, heavy items are best carried high and close to the shoulder blades.

Anyhoo, canisters are miserable things to pack and a good many packs simply don't accommodate them. If you know you must carry one, I'd find a pack that lets you store it inside with the option of vertical and horizontal carry. Lighter items like sleeping pads can go outside the main compartment with ease, and without upsetting the load balance. Packs with long extension collars might allow keeping it all inside. For those that don't, in my experience, as the canister empties and I can transfer gear into it, I can eventually pack most everything inside the main pack compartment during the course of the trip.

My $.02

Quote:
I have been kicking around just a little, on whether to buy a new pack next Spring, or use my old Epperson pack as I am selling my scuffed up Golite Gust to one of our members here later this winter. Question, I seem to be consumed with getting another super light pack like the Gust, (20 oz.) or go with a little bit heavier pack, like a Mariposa, Vapor Trail, Jam2, Zpack, or do you like to use a pack where all your gear can go inside, or do you choose to use a lighter pack and strap some gear on the outside? My issue is getting a Garcia canister inside. My old Camptrails pack, when I gave it away, that is what I had to do for a long trip. When I was doing some research for a new pack, (my Epperson), I realized my old pack was suitable for a weekend.:) Any observations would be helpful. I may not even get a new pack as I am paying my credit card down now as I made plane reservations for a AK trip next August and they charge your card right away. Any threads on this topic, please point me to them, I did some searching last week and couldn't come up with much. Thank you.
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--Rick