It sounds like you have a really good perspective.

I also get that there is conflict within you, regarding his current positives and his past negatives.

Are these things that you still "holding against him" what you would consider "deal breakers?" IOW, were those things why you left the R?

Also, do you feel he is being cautious, or does it feel to you like his guard is down? Do you get any feeling that he might be thinking about getting into a new R with you?

As you see positive change in him, do you feel he couldn't or wouldn't (or didn't) change those negative things? Are you afraid he didn't or wouldn't?

While you are considering a deeper, more connected R with him, are you prepared for the possibility that he may just want to be friends, even if he's changed the negative things?