So my coverage is maximum out of pocket per year $5-7k. It's very reasonable to assume HN readers make more than $50-70k/yr, so that's better than 10% of income for the same coverage. (I also think the top US care, if you are in the right place, is better than the top NHS care, but only for cancer or very rare diseases; for everything common they're comparable, but NHS covers everyone, so the average quality of care in the UK is better than the average in the US (rather, the 25th percentile care in the US is horrible, whereas the 25th percentile in the NHS is pretty comparable to any NHS care)
(and, with an HSA, if I spend less than $3-5k/yr, I get to put that money pre-tax into a Roth IRA equivalent retirement account. I generally spend $200-1000/yr on medical care, so this tends to work out well for me; I don't think I've ever spent more than $1500 in a year. A lot of employers will just give you that money (and pay your premium) if you pick an HSA plan vs. a PPO plan, since it saves them approximately that much in premium)
I'd be willing to pay some premium to cover everyone in the country vs. just myself, and to ensure I would have full coverage regardless of income. I don't think I'd want to pay a flat 10% on all of my income without limit for that, on top of taxes, though. (although, between medicare and 3.8% obamacare surcharge on income and capital gains, it's already nearly 10% up to 100k)
In addition to HSA, what I'd really like is truly universal minimum standard of care -- not quite where the NHS is, but maybe 20% of that -- to cover preventive and "very cost effective" treatments. The problem is while the NHS is able to use QALYs in making decisions, I don't think the US government would be so rational; we'd end up over-covering dramatic diseases and under-covering less dramatic diseases. I don't believe a $500k intervention for an indigent old person with limited benefit should be paid by taxes, since that same $500k could cover childhood immunizations or preventive care for 5-10k people.