For anybody interested in an update on this, I shall be applying for a number of programs over the next 2 or 3 days (aiming to send all applications by Friday).
I have taken the prevailing advice regarding masters vs PhD, and am applying to 5 good UK Masters programs in epidemiology, albeit with a goal of applying to PhD positions afterwards. The exceptions to this are a funded PhD program at Toronto in statistics, which I applied for early in my decision making, and two absolutely excellent, fully funded epidemiology PhD programs in the UK that offer the option of beginning with a Masters. The latter two simply looked too good not to apply to.
I have a plan of resitting the GRE, before academic pressures begin in earnest with the beginning of whichever program I end up at. I am convinced I could get very high scores across the board with it being my sole focus for a while, and with learning difficulty adjustment (i.e extra time). I would then be in a position of being able to apply to US epidemiology PhD programs with an excellent GRE, and an epidemiology masters.
The last paragraph is getting WAY too far ahead of myself, an presumes the occurrence of several events which could very well not come to pass, but I find it fun to think ahead. I'll post an update if anything relevant comes along, although perhaps nobody cares, and I am screaming, narcissistically, into the void. Thanks everyone for advice so far. It's been very helpful.