Sounds like you just suck at the class. I went shield till 37, then respeced to assault at 40. You loose a ton of survivability but gain a good bit of DPS. The game gets way harder in Act 2, its the same for any class.

Respec, why are you splitting your points up like that? You're 27 so you are missing either a) smoke grenade, b) gut or c) Incendiary Round. Pick a tree and stick with it. Those skills are important to proc HIB (well not smoke grenade, but ion cell DOT in shield is) . I personally went Sheild till 37 and went armortech to make my own gear. When running with Elara I had no downtime and could solo boss level mobs (the white star, not the yellow ones) with to problem, though it took a little longer. At 37 I switched to Assault to try out a dps build and something different for PVP, way less survibabilty so it was more difficult but still very doable and a lot of fun in PVP. Way less of an in your face style, more kiting and in and out play. It sounds to me like your doing it wrong. If you can't survive, switch to full shield and it will be way easier. Use stockstrike to proc your ion cell, then use high impact bolt and then sticky grenade whenever off CD. Use hammer shots in between attacks to conserve ammo and elara to heal.

What are the details of your spec? How far did you run up shield?

Currently a level 41 Vanguard, and I've been fooling around with the different trees. I initially leveled to 37 with shield spec then switched to Assault since I was tired of having no DPS. I found that my survivability was reduced by an INSANE amount. I used to be able to solo anything with Elara out. Anyway, I'm looking to switch to tactics to try and find a middle ground between surviability and DPS (especially in PVP). Does anyone have any input between the trade offs between using high eneregy cell and ion cell while in Tactics spec? Would I be missing out on much DPS and ammo regen by switching? How important is that extra movement speed? And should I be considering a dual shield/tactics spec instead for storm and such?

If you're going for a ball carrier spec that is pretty poor. The best talent we have for that is Storm and you need more defense. There is no good ball carrier & dps spec.

Hybrid specs can work, it depends on your style. Mainly the shield tree's top talent can be argued that it's skippable. The other tree's top talents i wouldn't skip unless you were going to be experimenting with something else. Also any of the trees can PVP at the moment. Unless you're in high end pvp where that extra 2% damage will mean something. Obviously each tree has it's strength. Plus you need to remember that winning in warzons is never about getting the most kills, it's meeting the objective. Hence DOTs to prevent captures and improved harpoon stun may not seems like super great talents but can be excellent when used correctly.

Just want to say that if you are relying on gut to proc for HIB and you're a shield spec, then your doing something horribly wrong. Gut is only needed in tactic spec w/ high energy cell since they can't proc a dot from ion cell or plasma and have no additional CC such as storm. In my limited PVP experience so far I have rarely had a time where i couldn't cast HIB on someone. And if I couldnt I was only a stockstrike away from being able to.