On Backpacks:

Internal or External Frame? 

This one was never even an issue to me.  Internal frame all the way.  Lower weight, better balance, less prone to damage and if you ask me...more comfortable--you ever carry an external frame pack and hit the back of your head on the frame? Not fun. 

Plus...they look cooler. 

My SCUBA instructor has a rule...the number ONE rule, that is, for diving.  Always look good. 
Why not apply the same to hikers? 

Seriously though.  Please bear in mind the MOST important rule in a hike.  I haven't mentioned it elsewhere so I will throw it in here while I can...

"Hike your own Hike".

I'm not sure exactly where I picked this phrase up, or to whom it should be credited, but it truly is the most vital aspect of your planning.  What works for me might not work for you, etc.

Now...back to backpacks...

I have gone through a lot of consideration on the pack I will carry from my thru-hike.  Unfortunetly, there are no outdoors stores like REI or The North Face or really *anything* for thousands of miles from me.  This means I've had to do everything via internet and will have to mail order. 

This creates problems in terms of fit and comfort...particually when it comes to the weight load.  As I currently plan to do some long stretches without resupply, i will be carrying some farely hefty loads, possibly even upwards of 60 to 65 pounds. 

I have gone through a lot of different packs and I have read a LOT of reviews on various manufacturers and specific packs. 

The following is a list of the major manufacturers that make the "good" internal frame packs: 

Gregory
Mountainsmith
Osprey
Dana Designs
Arc'Teryx

this is by no means all all exhaustive list.  I have heard some good things about VauDe, Lowe, and Searratus as well...but i didn't look into them too much.  From my research, it seems that any pack by the above mentioned companies will be a good investment if fitted and applied properly. 

The following are the packs that I have considered: 

Gregory Reality 02

This is the pack that I first picked out of the litter.  I really liked the buzz I'd heard about Gregory packs, and how they are so custom fitted.  I like the seperate sleeping bag compartment, the air flow system, the weight of the pack, the hydration bladder pocket...However...as my plans progressed I realized I just couln't bring myself to the level of the ultralights.  I don't like some of the concepts endorsed by that mentality and I certainly have logistical problems with such lightweight methods (particually preparing the food ahead of time).  This pack doesn't do very well holding over 35 pounds.  I also began to doubt that the capacity would be enough. 

Gregory Forester 02

My second choice.  Again, Gregory. While this one seemed a better choice than the Reality, the same issues came up.

Gregory Shasta 02

Designed for a heavier load, to include the one I will be carrying at times, this pack seemed the perfect choice.  All the convenience and comfort of a Gregory, with the load bearing suspension I required...However... 

Mountainsmith Specter 02

Right now, this is my current favorite.  I looked at this one a lot earlier one but discarded it because I thought it was too big for my torso.  I finally picked up a fabric tape measurer and got an accurate measurement.  I'm just shy of 18 inches.  That makes the Specter fit my frame.  It also means that I would have to upsize the Gregory from a small to a medium...pushing the weight up on the Gregory selections.  So then...the Gregory Shasta, at a size medium...topped the scale at 6 pounds, 2 ozs.  The Specter, on the other hand, weighs in at a paltry 4 pounds, 5 ozs. 
That's almost TWO POUNDS lighter.  As I went up the ranks of Gregory packs, the weight kept going up...and I thought to myself..."OK, it's heavier, but it will work better for my needs".  A Gregory, sized small (as I initially believed I needed) is 5lbs 12ozs.  I thought to myself...well OK...I SUPPOSE I can live with that. 

But then....the Specter.  I have several 10+ days straight through without resupply.  My last stretch is planned for nearly two full weeks.  That is a LOT of food and food weight.  Two pounds is about what one day's food will weight in at.  That food will also take up a TON of space...and the Specter has 5600 cu inches of space...600 more than the Shasta. 

Based on all of this, I think I can sacrifice the sleeping bag compartment.  I wanted a pack with a side entrance anyways... 

Not having a place to lash my ice axe will be a hindrance...but I think I can fashion something in that vein. 

The Gregory line may prove to be a more comfortable pack, but the Specter has gotten some really good reviews...and to be honest...considering what I am doing the majority of my training hikes with:

Military Issue Large ALICE (All weather Lightweight Carrying Equipment) Pack w/ Frame 

I think pretty much anything commericially produced with a real suspension system and an actual hip transfer function will be a marvel of creation in comparison.  You might not be able to tell from the picture but that "hip belt" is nothing more than a kidney pad...it does not support the frame at all.  In fact, I don't even buckle it.  These things are not designed for comfort.  They are designed to be parachuted with (to make a long story short...they routinely hit the ground first, (via a lowering line) from the equivalent of a second story+ fall), carried through hell and back afterwards, and survive...all while carrying loads of 100 pounds or more (that's not a typo).

My theory is that if I can routinely do 20 miles carrying 60 pounds with THIS thing...well then, I've got it made.  I will probably only spend the last couple months of my training with the pack I intend to use on the trail...