Scola and Martin for Pau is a pretty even deal.
So as Lowry and Scola but the Rockets are better off keeping Lowry. He's a all star level point guard who not only can pass the ball well, but plays very good defense. There's not a lot of those in te NBA. Kevin Martin's scoring can be replaced thru FA.
I like Dragic as a Point Guard more than Lowry, but I think it's in the Rockets best interest to hold onto both to start the season at least. Dragic looked fantastic when given the opportunity, but I'd want to see him do it for a little longer before trading away a player as capable as Lowry.
Dragic looked to be the better scorer, but he's not as capable a passer, defender, or leader. He is also, however, a better defender of Sasha Vujacic.
I'm sure I haven't watched nearly as many Rockets game as you have, but definitely a better passer and leader, IP (this is an honest question not a 'you kidding me' kind of statement)?
From what I've seen it seems like Dragic handle/ability to create allowed for a lot of open looks for his teammates.
They do it different ways from what I've seen, Lowry penetrates and dishes more for his assists.
Dragic also has a good midrange game, he can hit short pull up shots within the 3 point line and has the little floater in the lane. Lowry spends far more time either behind the line or at the rim, his mid-range game is putrid. (but he knows that at least and doesn't take a ton of them preferring either a normal jumpshot or a drive)
Strangely Dragic finished at an amazing clip for a guard, around 70% at the rim.