Looks great, Jamie. I don't own any of Artificer's custom creations, but I've seen his work in person (on others) and I have no doubt it's as high a quality piece as money can buy. I love that he's making new brass cantles in a historical style.

The first is that the highly polished brass needs to be polished regularly if you want it to stay highly polished. Since I have an antique brass waist plate as well as a bright brass one (both from Jerry over at Stillwater Kilts) I'm tempted to see how the brass looks if I let it develop a bit of a patina.
Yep, that's the problem with brass. Those of us with MOD cantles which have been polished are struggling with the same issue. You either have to polish it every time you want to use it, or just let it develop a patina. There is no in between. If I even lay one finger on it, my fingerprint immediately begins to turn a different colour. And you'll notice over time, too, that anywhere the brass touches the leather, it will discolour differently (more aggressively). Polishing it with those leather laces through the cantle looks like a headache. Good luck!

The second is that the brass loops on the back of the sporran require a simple belt, instead of a regular sporran belt designed to clip onto the D rings at the back of the sporran.
Huh, I was unaware that the clip-style sporran belt was considered a "regular" sporran belt. Most of the traditional sporrans I've seen were designed to use a simple belt. If you really do like the clip style, I'd bet you could have Artificer make you a conversion piece that goes through the brass rings and has a separate small D-ring. Although personally I think using a simple belt through the brass rings is far superior...

(By the way, side note: I really dig that jacket you're wearing with your IoS kilt!)