I think it depends on what you are looking for in a relationship. If you want to live with someone in the long-run this might be a non-starter, but it might be ok. I think it is fine to decide someone is not for you for whatever reason.
I think you need to start talking to him about your concerns, even though it will be a very difficult conversation for him. It sounds to me like some of your concerns might be misplaced, or based on guessing how he is or might be with certain situations. It would be better to make decisions based on the facts. M.E. is a fluctuating condition though so he won't be able to give you absolute guarantees, but he might be fairly stable for a long-time now so he might have a good idea of how he is likely to be. As it is early days you might also be looking for different things from a relationship (this can happen with any relationship obviously).
I also think that that some of your concerns are hangovers from previous relationships. You are right to be careful if you have been bitten before, but I think you might be jumping the gun a bit by worrying about this person being potentially needy.
Normally when people use that term they mean emotionally needy and possibly not giving enough emotionally. In my experience a lot of people with physical health problems are very resilient and much less emotionally needy/underdeveloped than the average person, especially if they have been sick/disabled for a long time and have adjusted to the disability. This won't be the case with everyone with a physical condition however, so you would need to judge on a case by case basis. Often people with a physical health problem have to become emotionally resilient but also generally have a greater understanding of different lives/perspectives than the average person, and in my opinion are often emotionally healthier out of necessity but possibly also due to having more time to think about things, make adjustments etc. But again this won't always be the case.
Personally I sometimes find people who have had relatively easy/"normal" lives can lack coping skills if things go even slightly wrong, or they sometimes some sound to me like they complain a lot about things that seem minor. I am generalising I know, and I might just have had some unlucky/atypical experiences. I would have a bit of a preference now to have friendships/relationships with people who have had some sort of major difficulty they had to overcome in their life, although this is partly as they might understand me better (I have M.E. myself).
Someone with a disability/illness might have more time to be there for you, if they are not working, and might be able to prioritise you in a way a healthy person might not if they are very busy, or are a workaholic etc. They might also be more appreciative of your positive qualities, in a way that someone else might not notice as much. Disability is not solely going to cause negative problems and it might add to the persons character, in a way that going through any life-changing event might.
I have M.E. myself, and have been sick for a long time and have had a lot of contact with ME patients over the years. Most of them are not emotionally draining at all. I am fairly sick myself but I am friends with people who are much worse, e..g bedbound, and I do not find them draining at all. Actually they are quite hilarious and I feel I get a lot from them. These are definitely two-sided friendships. But sometimes people have though times, like anyone. However the exception to this general rule in MY experience is people who also have some sort of psychiatric problem, who I have often found very draining. However even there is it not always the case. So again case by case basis.
I do think you need to make a decision about what suits you and what your limitations are, but that might be hard to do at this stage as you might not know him that well, or to be honest know yourself enough either (I mean that sometimes people say they couldn't cope with something but then they are in the situation and they do).
So this is a sort of long-winded way of saying, talk to him openly about your concerns so that at least you are basing your decision on facts. You also need to think about what you want out of a relationship in the sort and long-term. Personally I can't see myself ever moving in with someone as I like my independence and would fear becoming financially dependent on someone and potentially ending up homeless if we split up. I see so many relationships ending/"failing" that I think probably most relationships are better viewed as temporary, even if long-term. I would prefer if I met someone to be in a relationship that was committed but that we wouldn't live together. But not everyone thinks like this.
Eek I have just previewed this message and it is looooooooong. Sorry about that everyone.
