Stuff like this gets me excited. Although it IS better to have some healers and other classes in your guild, I've done plenty of 5-mans with nothing but my other members of my guild's "hunter possee." (to include LBRS...and with nothing more than blues and a few pvp epics for gear). Have one pure Beast Spec to tank (usually with a screeching, growling bird), mend pet (maybe) and give Ferocious Inspiration. Have at least one marksman for improved hunter's mark and trueshot aura. Have at least 1 survivalist for Wyvern sting and Expose Weakness. EVERYONE has 3/3 Entrapment and 2/2 Clever Traps for CC and Entrapment frost slick that everyone can kite back and forth across. Have everyone coordinate their stun/interrupts over Teamspeak (Intimidate, Silencing Shot, Scatter). Have plenty of engineers for bombs and jumper cables that will invariably fail. Oh...and one other minor HAS to know what they're doing...and how to play "hot potato" with particularly tough mobs/bosses and adds.
Of course, deaths happen, and this isn't exactly efficient for getting drops...but it's plenty fun; cures boredom and everybody learns a new trick/technique or two. -~NibbsA Guild is best when it brings people together who can lend mutual assistance and complementary skills to each other.
Do what you want in the game, and good luck to you. But I suspect that your Hunter-only Guild will find that there will be more conflict because everyone will want the same drops, there will be a lack of Healing in your groups, and a lot of BOP drops more suitable for other classes will be picked up for vendoring or will be DE rather than being used.
On the other hand, each group of 5 will have 5 Pets to assist, and it might be a lot of fun. Let me know if it works out, and be sure to get good screen shots. -Hunter Pet information links:
Good Intentions Guild
Petopia
TKA SomethingOut of curiosity, what would be the purpose of a
Than=x =D--Executus-
Romordi
Level 80 Dwarf Hunter
[Advent]
Cella
Level 70 Night Elf Druid
[Advent]
Peppery
Level 19 Twink Rogue
[Spankin Bank]