I posted in your other thread about your spec, but I'll move to the discussion here!
I don't know how blood compares to 2H frost for single target as I haven't been 2H frost since my first raid where I found the threat to be horrible. Dual Wield frost is out and out the best spec for threat at the moment, and as you're a fan of frost I would suggest giving it a go if you can get your hands on a decent pair of weapons (Frost Giant's Cleaver is perfect, for example). It's also a more involved spec to play than blood.
I'm currently MTing as blood. I switched from DW frost for heroic encounters as the healers found me tricky to keep up at times and I gain a lot of health, better self healing and a much nicer minor cooldown and they've found it much smoother since. My single target TPS is very good, but it does struggle a bit with aoe. I can keep stuff on me but my DPS are impossible! The bad AoE complain if they pull agro single target DPSing and the good AoE complain pulling agro while AoE DPSing. That's trash though, and if they die I mock them. Blood is also very very very easy to play. Which if you're leading the raid or whatever leaves you a lot of spare brain to keep an eye on the fight and what everyone's doing and make sure there's nothing going wrong.
Out of interest why would you not want to go DW frost? Do you just like having a massive axe?
Could you not dual spec frost/blood and use one on trash and the other on bosses?