I'm conflicted over this issue. After losing a partner who died of AIDS, helplessly watching him slip away over weeks with nothing I could do, and finally passing away in my arms, I told myself at the time I'd never have another poz partner. I had knowingly and willingly accepted those risks, responsibilities & heartbreak once, but that was enough.
And indeed, my present partner is neg, as I am, but he does have some medical issues that concern us, as I have myself, not unusual for our age group. Naturally every situation is different, and if my current partner had HIV when we first met, I'm not sure how I would have handled it.
I really don't mind the inconvenience of living with someone with medical needs, provided they are within my ability to handle. In fact, since I present my own medical issues that HE must deal with, like epilepsy & heart disease, I like the idea that we are caring for each other, and prefer to think that we are mutually supportive, not mutually dependent. Neither takes, but both give.
But if I knew a potential partner's life was at risk, his future uncertain, I would have to think long & hard on that. I know what the loss of one partner did to me; I'm not sure I could go through another, and be left alone at my age. Caring for someone doesn't frighten me; having to bury him does.
Of course, all of life is a risk, and unexpected illness or injury could still take my partner from me at any time, or me from him. But I don't go looking for trouble, either, as they say, and so I guess I would selfishly consider serious health issues in my choice.
At least for a partner. The OP question is about dating, which might or might not lead to an LTR. For purely dating I would hardly give it a second thought.