Saying Jamal Murray has suspect character because he dosn't defend is way off. Its more like he has difficulty defending at a high level due to less than ideal athleticic ability. Not really a character flaw, more an inherent shortcoming that he makes up for on offense. Still a near ideal player to stick next to Smart with his decision making and shot creation.
Both could switch off playing lead guard and Smart could take the tougher backcourt matchup. From everything I've read about him Murray is a high character kid.
I would not consider that an Ideal pairing considering Murray's questionable ball handling and playmaking ability (< 1 AST:TO) - neither of which are really strengths of Smart's game.
There is also the issue of size and athleticism. Smart is 6'3" and Murray is 6'4" an neither is especially light on their feet athletically.
I actually think that would be a really poor pairing, personally.
Murray and Thomas would be bad also, because the defensive liability would be tremendously bad...though Murray's shooting would help Thomas in getting space offensively, I'm not sure if that would offset the horrible defence.
Rozier and Murray would probably be the best pairing, as Rozier can cover for Murray's lack of quickness and defensive limitations, and both guys can score.
I think Hield is a far, far better fit here. He's a much better athlete and a much better defensive player then Murray, he's bigger, and he's an even more dangerous shooter.