( Warning: big wall of text... )
I've had my eyes on these since this thread appeared here, and I finally was able to buy the set a few days ago. It's one of the most expensive sex toys purchases I have made, however I feel like I've struck gold with this one; totally worth the price!
The plug are extremely well made. Even holding them and feeling their surface is a pleasure. The weight is right, the smooth machined surface is somehow reassuring and satisfying, their pitch black color seems untaintable. Being made of metal, they heat up very fast under a hot water faucet, and keep their temperature for a long time. Surely, the reverse is also true, but I'm not tempted to go in that direction. I like comfy insertions.
I can take toys up to 6 cm with ease, and regularly play with 7 cm toys. So, the sizes in the set were a very good match to me. The small one (5 cm at its widest) is perfect for warm up. I can insert it with barely a hint of lube, and most likely keep it for hours on end. It does not hinder any of my movements, does not hurt in any way, but makes its presence felt in a very enjoyable way.
The medium one (6 cm at its widest) also enters rather easily, especially after being warmed up by the first. Here's a very pleasant thing by the way, when keeping such toys for more than an hour or so. The sphincter becomes used to the inner diameter (1.5 cm smaller than the widest point), so it is warm for bigger things, but it is not so used than getting the plug out, and the bigger one in, can still very much be felt. The medium plug can also be kept for a long time, about the same as the small one. It all depends on what you're used to and what you current limits are, of course. It barely hinders movement, though there is a small pinching of my butt cheeks when I seat down; they get around the base of the plug, and get pinched if I sit down without taking the precaution of slightly opening them. I also find that I need to push the plug a little bit, and wiggle my ass cheeks around sometimes, so that I can get rid of a small feeling of irritation down there, that slowly increases over time.
The big one (7 cm at its widest) enters the realm of serious business for me. After being warmed up by the previous ones, I can also take it without much difficulty, just needing to be a bit more generous with the lube, at the same time pushing a bit stronger, and taking a bit more time to do it. Still, I can take it just fine. It is a bit more of a pain than the medium one to sit down, because it is a bit longer, especially including its plug. Basically everything is slightly magnified compared to the medium one, including the small irritation that builds up over time. Still, I think I can take it for a while.
I find I can keep all these plugs for a few hours without any harness. Maybe it is because I don't use much lube, or because my ass is somewhat muscular. Surely, for much a longer time, or trying to sleep with them (not yet attempted), I would use some kind of rope work to ensure they don't get ejected accidentally.
Speaking of ejections... Make no mistake, the optional closing plugs that are available on the site are a mandatory purchase. Make sure to buy the corresponding sizes; if you buy the set, you need the three closing plugs. You'll be surprised at how much crap you hole puts out, including lots of mucus; understand that you will absolutely not feel it fall from the open hole. While this can be an exciting thought (I'm kind of a scat guy myself), it can also become a problem very fast; better have the choice here, depending on the mood and location, rather than finding yourself ordering the closing plugs a few hours or days after realizing your mistake... By the way, unless you fecal matter is extremely soft, almost running (eww...), don't except to have whole turds falling out of the holes; it's more like small pieces and mucus. You still get to release a huge turd when you finally remove the plug.
So far, I've mostly worn the plugs some evenings, for three or four hours at a time. I don't aspire to full-time plugging, but I'm interested in trying longer times during my week-ends and holidays. We'll see how it goes... I fully intend to enjoy these toys for a very long time.