Z7 is the smoothest bow I have pulled.

my martin is pretty smooth... but i havent shot a mathews. have shot my buddies hoyt, and it was very nice, but had a heavier draw which made it less smooth for me. im a lefty so i dont get to grab everyones bow and shoot it! yall are lucky haha

Ditto on the Diamond Black Ice.....

some of my favorite, and im a fan of the smooth draw... were the diamond black ice, mathews DXT, mathews Drenaline, and bear truth 2, the bear was set quite a bit lower in poundage than i usually shoot, but it seemed pretty smooth.
but the mathews DXT/Drenaline and the diamond Black Ice are sweet shootin bows!

The problem is that it all depends on his shoulders. I have rotator cup tendonitis (sp?) and I drew many many bows before buying one. I went with Bowtech because for ME it drew smoother than any of the others. I tried Mathews, Hoyt, PSE and a few others but for me the Bowtech was the easiest, smoothest draw. Take him to a pro shop and have him decide what draws best for him. Plain and simple.