Really strong addition to the Ergowear lineup. X4D's are normally my daily driver, but the HIP line has some nice distinguishing features that seem to have overtaken the X4D in my preferences.

The slightly more rigid fabric that comprises most of the garment feels somehow more supportive than the X4D and the trim is similarly more structured, without any perceivable negative consequences. The whole garment feels like it hugs your hips in a nice, not constricting way. The fabric does almost feel like it reaches too far along the sides to meet the waistband past the hip bone points, but I don't really feel or notice it. These are kind of a compromise for me between X4D and MAX Mesh because they're breathable but firmer, so also decent for athletic use.

The back strap is thinner than most of thong garments available here and pleasantly doesn't need to fold itself - it just kinda fits into place, I forget it's there, and can wear these from wake to sleep. I've already added two more to my top drawer since trying this one.

The perpendicular seam at the bottom of the strap/pouch is slightly further back than on the X4Ds, almost to the middle of the perineum, maybe an inch or so difference. This will be a bit less familiar to X4D wearers, where this seam is normally a bit further forward and causes slightly more lift/support. It hasn't been a negative for the HIP, just different and slightly unexpected.

There was a little bit of burling (three discernible spots) of the fabric on the front of my first pair but doesn't seem to have compromised the garment and didn't merit contacting customer support. Later purchases didn't have any burling.