Adding on to Rachel's comments on Iwata hakama...
The fabric moves well.
The straps are well constructed with more than one "casing" line (the lengthwise stitching up the center of the strap) which keeps the straps flatter longer and also prevents the straps from folding up and cutting into your body.
The koshita, even when brand new, is comfortable, although after you beat the hell out of it with ukemi it's REALLY comfortable.
The only mending I've had to do in 5+ years is around the stress points at the outside of the hip areas, but nothing major.
I'm five years into mine and I'm thinking I'll get another one this year before this one gets too ragtag or I go through the knees. Then I'll have a spare. I'm getting Iwata again. No contest.