Pet's HP should never be an issue, the same as the player's HP should never be an issue. It is far easier to move your own character than to move your pet if either should be dodging attacks. Pet's are more likely to die than the character for this reason, but either way I don't recommend Allocating VIT neither for yourself nor your pet even if Allocated VIT did count for the pet unless you really wanted to have Titan-Egi tank. I wouldn't trade 30 INT/PIE for 30 VIT directly. The only time you MIGHT need more VIT for PVE is for Twintania's Fireball. If this is the case then it's fine to Allocate VIT UNTIL you pass the HP threshold you need in gear.
If you want more VIT then it's best to meld it to jewelry as opposed to using Allocated VIT since your pet benefits as well. Full i70 crafted can have 45 INT, 45 MND, 45 VIT and 30 PIE. This is a gain of 45 MND, 45 VIT, and 30 PIE at the loss of -20 INT over full i90. More VIT AND less of a loss in INT than Allocating 30 VIT instead of INT and/or PIE.
If your Allocating VIT I don't know what the point in going for BiS is when you care about HP so much yet pushing for DPS everywhere else. If you value HP the most then get HP in both Allocation and Gear. Doing only Allocation is the worst case scenario IMO.
If you you want BiS IMO full i70 crafted is better for SMN for the gains in PIE (able to sustain full DPS for longer and conserve more Aethers for bursting mechanics (which is going to secure more wins than +5% dps in unhindered environments)) and extra secondary stats which is better than 20 INT overall. A SMN will never have any issues in a non-hindered environment no matter whether he has BiS or not so it's best to gear for when it does. But if you want to stick to the non-crafted gear for BiS for your DPS then Allocating VIT seems silly since this will lower your DPS potential for PVE. For PVP then maybe Allocating VIT is good but again if you value HP then get it in every place you can.