Ranger Danger
Things will certainly be interesting with 3 Rangers. The first few encounters are quite easy so there won't be any problems there. But as the module heats up the encounters start to get a bit tougher and towards the end there are some very challenging issues for you to face. Some of these will require a certain amount of creativity and, more to the point, diversity to conquer. As it is you are only a 3 person party rather than the recommended 4, so you are already a little behind the 8-ball diversity wise.
Whatever Floats your Boat
Having said that, if you all want to play rangers then who am I to say "no". It will certainly make knowing each other easy and it will sure make for an interesting game. What I'd really hate to see, though, is that I spend 50-100 hours working on the campaign (and I've already put in a
lot of hours) only to have it fizzle out after a session or two because the party balance is so screwy you can't accomplish anything. I'm just throwing it out there that some consideration would be appreciated if it ends up so messed up you can't help but get killed and have to start a new character.
On the plus side, an all-ranger group limits the amount of reading on classes I need to do.
Time Heals all Wounds
Rubbish.
Magic is what heals all wounds. You may want to consider to whom you will be turning when all these rangers need patching up. Maybe you wont need it. You'll probably be lousy with
Cure Light Wounds when you finally hit level 7, I'm sure no one will need healing before then, what with the heavy reliance on non-confrontational role-playing you're all known for :-)
On the plus side, I haven't read any of the spell casting bits yet, so that might save me a lot of research too. I should probably read the wound stabilisation and dying rules pretty thoroughly though.
All the Classes Rock
From what I can tell, PF has made all the core classes pretty awesome. I don't pretend to have read them all, but just as an example, I think
Bard has become a pretty playable class now.
Spells from level 1 and pretty decent combat capability. It appears that
Leonard Cohen is a level 20 bard with his ability to depress you so much with his songs that you literally take your own life. This
Bardic Performance stuff is on top of spells and from what I can see basically gives about 6 spell like effects per day at first level (assuming CHA 14) going up by 2 per level. So a 4rd level bard (with just 14 cha) is ripping out 12 performances a day plus plus 7 spells.
Fighters get more feats than a centipede and Druids can get all companioned up with pet
wolf/bear/etc at lvl 1 as another couple of examples. Barbarians can get a bit crazy too--+8 str rage bonus (and x1.5 damage bonus for 2 hander) combined with auto critical hit anyone? If you fancy being a Barbarian but don't want to be a Shoanti, you can be a shipwrecked Linnorm (viking) who has been living in Sandpoint for a number of years. Though obviously you're a long way from home and no free Shoanti totem spirit. You still wont have any healing but at east you'll have d12 hit dice :-)