I posted in both those threads, but in a nutshell I love mace (and clubbell) swinging and think it's a great complement to KB lifting.
I'm currently dealing with a severe rotator cuff tear (suffered while playing basketball, not training) that is going to require surgery, and mace swinging is something I can still do without pain. In fact, it's helped keep my shoulder functional to an extent that has surprised my doctors.
BTW, my maces are plate loadable maces from Strongergrip.com (don't know if they ship to the UK, or what kinds of maces are available over there). I have a thicker handled one (1.66") with a 42" handle, and a thinner handled one (1.33") with a 48" handle. The plate loading system on these works really well and is very secure. It's not very convenient to quickly change plates, but I don't change weights very often (I currently have both loaded to a little over 20lbs). It's more useful for adding weight over time without having to buy separate fixed weight maces. They also have a nice ball end, whereas the most commonly available maces here in the US (such as Onnit) have a straight end to the grip.
The ShoulderRok looks cool, but is the same length as my longer mace which a little too long to use indoors in my house with 8ft ceilings (I can use it, but have to be very careful not to hold it too high, and so I stick to the shorter one in the house).
Annoyingly I've just deleted a video of myself using my 4kg otherwise I could've posted.... Yes it's light but feels great for my starting point. I have an 8kg waiting to go but I think this 4 will keep me going for a while..
I saw one that Steve Maxwell had made from a basketball filled with concrete, so I made one very similar. I used a half size basketball like Steve used and 1 1/2" galvanised pipe for a handle. I put a few roofing screws in the pipe to give the concrete something to secure itself to & prevent the handle slipping out. It's How You Put it Together...: Gitchy Gitchy Gada Ya-Ya!
The weight seemed to be about right for someone my size as a starting point & I was getting a good workout with it but I kept tweaking my dodgy shoulder with it. Now it just sits in the shed.
Sorry to dredge up the old post me old mucker but thinking of getting a strength shop mace myself. How did you get on with yours. Do you still get plenty of mileage out of it and the big question how do the fair with low ceilings? Standard British council house