OK... So I've had the Swazi Tahr for a while now and feel like I can weigh in with my thoughts on this jacket.
First of all... Expensive. Swazi is a known brand and you're paying a certain amount for the name. However, their reputation is well deserved. This anorak is well-designed and the workmanship is fantastic. It is also quite heartening to know that Swazi recognizes that TriLam shells can get perforated in the field and their guarantee covers that possibility/eventuality. They explain in advance what you may experience and what measures they will take to repair your gear. I'm quite satisfied with this arrangement. And just to allay any concerns, this is a very robust jacket. You are not going to have to be extra careful with it. Just remember that like any jacket, you can poke a hole in it.
Insulation quality: This is essentially a TriLam shell - which means it is a shell that you layer insulating clothing under. I live in Florida so it isn't exactly arctic conditions here, but I have been Diving trilaminate shell drysuits for years. As such I would advise having a close-fitting wicking layer against your skin and then loose layers on top. Steer clear of cotton as it has ZERO insulation property and if it gets wet, all it does is hold the wetness against you. This is a recipe for hypothermia. I'm a big fan of polypropylene, wool, and fleece.
As I said I live in Florida. We've had some driving rain and heavy winds lately and this jacket has done great. The temperature is about 80 degrees Fahrenheit so I'm only wearing a short sleeved t-shirt. Given the design of the anorak I would encourage wearing long pants. Otherwise you might get some interesting looks from people. But I digress.... Anyway, it kept me perfectly dry and was a really nice barrier against the wind. This is the first hood I have ever had that incorporated the use of a wire frame. It really is nice. It helps keep the hood nice and open but it is adjustable to your needs at any given time. Given the temperature I kept my hood wide open which permitted wind to flow through my hood and into my coat thus keeping me comfortable.
Breathability: Not sure I can give a well educated assessment on that as of yet. Once I layer up and use this anorak, I can speak more on the subject. However when wearing light clothing, I found myself wishing I had pit-zips. Those would have been nice. However, the front of the anorak opens WIDE and the hood frame keeps the face of the hood nice and open - and when you add that to opening the cuffs of your sleeves you can get some really good circulation/ventilation. All in all I have no complaints - just an... awareness of when I may need to make adjustments.
Size choice: I've always gone with an XL with my coats and shirts. I'm no longer particularly...burly. But I have a moderately athletic build. Given the measurement guide the website provided I could have fit into a LARGE. I ordered both to see which I preferred. (BTW customer service was fantastic - They extended the 2 week grace period for me as it was international shipping). In truth, the LARGE fit fine, but I went with the EXTRA LARGE anyway. The LARGE simply felt like it was possibly a little constricting. The XL was baggier but it I had unhindered free range of motion. The more I wear it, the happier I am I chose XL.
In conclusion, I really am happy with this jacket. I love the design and it is obvious that the folks behind it knew what they were about. I would also say that the quality control they exercise is formidable. Yes this is a very expensive anorak. Yes there are other fantastic products out there that could do the same thing this one does. However I chose the Swazi Tahr and I definitely got what I paid for. I have been places where I have been truly cold and wet and (apparently) I am willing to pay a premium to lessen that experience. If I had it to do all over again, I would still buy the Tahr.