Likeable heroes and heroines

Before she began Emma , Jane Austen wrote, "I am going to take a heroine whom no one but myself will much like." I think she was wrong; certainly these days most readers like Emma. The heroine we don't like is Fanny Price, so outwardly meek while inwardly censorious about everyone else. It's the strength of a good book that we can have an opinion of the characters not necessarily the same as the author's.
I'm getting towards the end of the first draft of Unofficial Girl - 73,000 words out of an estimated 80,000 - and I've started wondering whether readers will like Nick Cavanagh, a spec op and one of the three main characters. He elbowed his way into a major role, ousting the disabled Marine who was to have been a key player in the story. Beth becomes romantically involved with him, believing he is there to protect her; in fact, he's hunting her replica. He's unscrupulous on occasion, an opportunist, ruthless and fairly selfish. But I like him. (I think the daughter does too, since she was disappointed when it emerged he is 5'10". She prefers taller men.)
I'm just writing the scene where the two Beths, the original and her identical copy, get together for the first time. Nick has tried and failed to get Beth One on her own and give her an edited version of events which will show him in a better light, and Beth Two is about to tell all.
Beth Two took the stool next to Beth and began to eat, apparently in no hurry to enlighten her. Her demeanour was relaxed and blithe, as if she might whistle were she not eating. Nick made himself a coffee while helplessly waiting for the truth to emerge like a rat from a toilet.