I ride with an Escape 15. Shovel and probe in the pack. (2nd probe and shovel on the back of the sled, more on that later)
The only shovel that fit inside the way I wanted was a Black Diamond. Not sure the model, but blue blade and silver shovel shaft, black handle. I looked at many shovels, but didn't want one so big that the blade could interfere with the mechanics of the valves on the air bags.
Black Diamond 3 meter aluminum probe fits inside as well.
I do not want any of these outside the pack. If I get separated from my sled, I want to make sure that I have gear to survive, inside with other survival gear.
As mentioned above, I carry a second shovel and probe on the back of the sled. I use these when digging out and for initial search. If I have to take off my pack to get a shovel, it is useless, especially if I am at risk of getting caught in a slide (stuck on the side of the hill) or barried by hang fire - if I didn't see it and stay away from a rescue situation in the first place (and put myself in danger along with someone that is burried). In addition, I can always give xtra the probe and shovel to someone that passes by to help. My pack never leaves my back until I'm off the mountain.
I was caught in a slide 4 years ago. I can tell you it's like getting tossed around in a big cloths dryer. You don't have any clue which way is up. Maybe you will see light for a brief moment or two. If you hit anything, (I didn't, fortuantely) it will be all you can do to hang on to what is on your back. These packs have leg straps and waist strap for a reason. A regular pack won't stay with you.
In the end, I want everything inside the pack. And make sure the pack will stay on my back. I encourage everyone else to do the same so that you too can live to ride again another day.