I'll preface this post by saying I've been a Swanndri fan for a number of years, and have gotten a lot of use out of their secondary-flagship product (is that a term? I don't know what ship follows flagship in the pecking order) the Swanndri Ranger bushshirt.
The magic of Swanndri is that they can almost universally overcome the wearers better judgment and earn huge esteem despite their obvious faults. Despite still loving my rangers I have become more honest with myself; the cuffs suck, the center front gusset is dumb, the fit is pretty poor, the zipper isn't the best and the weave is pretty loose. I have taken in the sides of two of my rangers (because my waist is actually smaller then my chest, despite what the swanni designers expect) and made one of them a short-sleeved garment and have found them much more useful for it, but with the lack of wind resistance they really are closer to a sweater then a shirt in their use.
So what does the BMC pullover offer? By all appearances a much tighter weave, smarter fit, large flap pockets, a button front, better cuffs, and overall a more refined appearance.
Some of those are guesses, but I have not seen a Pendleton wool fabric that is looser then the swanndri ranger, and all of the photos suggest a heavier-then-shirtweight that very much appeals to me. Even just the rounded pockets and flaps speak of higher attention to detail then the relatively crude swanndri. The placket is deeper than the swanndri as well, extending to the bottom of the pockets for better venting and easier donning and doffing. I've no doubt that the designers were aware of the ranger when they made this but they have certainly improved on it. The other design they obviously were inspired by is the WWI wool Army shirt:
Pendleton and Woolrich both have examples of wool pull-over shirts in their histories, but often with only one pocket or a zipper opening.
The icing on the cake for me though is one feature I have never seen before:
An elbow reinforcement that is one piece with the sleeve placket. Someone was really thinking when they came up with that one (or had access to vintage garments I've never seen before). Echoing the army pullover but thankfully not being limited by it.
My hesitation with elbow patches is that often they don't actually end up under the users elbow during use, but the photos imply that these in fact do:
What don't I like about this garment? well I'm not to keen on the cotton lining and I'd like to see a second button on the sleeve placket but those are hardly dealbreakers. The price is out of my range but hardly out of line with a small run american made wool garment.
I have found a heavy wool pull-over shirt to be a very versatile garment in my wardrobe, something akin to a heritage softshell jacket and the BMC pullover appears to be the best game in town currently.