I've had the fabric and pattern for this sitting around for nearly a year and finally sewed it up.
I cut a sz20 with a 1.5" upper arm adjustment but otherwise the fit is out of the envelope. I'm not really happy with it I have to admit, I'm counting this as a muslin as it doesn't fit quite right - I can see the pulling at the bust, its too short and it needs a forward shoulder adjustment as it keeps tugging itself backwards. I will sew it again, the StyleArc patterns are a bit too expensive to only sew up once and I really do need a couple of nice fitting polo tops!
Fabric is a waffle knit from The Fabric Store and the buttons are shell ones.
So the good: I think the sizing is pretty good, it fits just like a sz20 RTW polo does and it doesn't worry me that I need to do a couple of adjustments before I'm really happy with the fit.
The bad: The placket instructions are awful, I know they are always a bit sparse but this pattern has some illustrated ones as well. I've sewn a few plackets now (3 or 4 of the Banskia Top MN 2102) and even though the StyleArc instructions were different I thought I'd go with them. At the bottom of the placket where you sew through all layers to finish it off there are 9 layers of fabric to sew through and it just doesn't look neat.
I highly recommend the Banksia top placket instructions, there is a lot less layers and a lot nicer finish to it compared to the StyleArc instructions (and I'll be using it instead next time!)
I'm not really happy with the finish of the collar stand either but I haven't sewn enough shirts to know any tricks to finishing it neatly (it has you topstitch it down and my stitching looks really wonky, maybe I should have hand stitched it down instead to make it neater?).
I have to admit I don't like sewing exercise clothes. I struggle to find the right type of fabric locally and I tend to either add way too much ease or not enough. However, I am so picky about fit now and after trying on that many pairs of RTW leggings looking for a decent fit I had to give in and make some!
This is the Monica pant by StyleArc. Its a sz20 graded in at the waist by a couple of inches. Fabric is leftover grey Supplex and the purple is dance lycra from Lincraft.
I found a couple of mistakes on the pattern, the gusset says to cut 2 but the instructions say to cut 1 - you are meant to only cut one. Plus the notches are back to front on the knee and lower leg piece. Otherwise they went together fine.