I'd caution against this a little. APC New Standards are even tighter in the thigh (relative to same waist measurements) and have more taper from knee to hem.
Everyone fits into stuff a little different, but just wanted to mention that.
I recently tried on the 3sixteen+ 30BSP, and it actually fits very similar to the Rivets, w/ two things to note: Rise is a touch higher, and it's a very different fabric (obviously)
Frankly, the Armoury jeans on the site at Epaulet seem pretty close, really...