I agree with you on everything you said. This quote is also a key factor. I’m a big fan of the Shield Platform (probably cause my first gun was a Shield). I simply like the Shield 45 more than the 9mm. I bought it really to be a back up gun and a range toy chambered in .45, but I loved it so much I just started carrying it (I’m not alone, I’ve read online and many shield guys do the same)
I’ll probably be sticking with the Shield 45 because I have consistently carried it for almost a year now, and it is the gun I have the most range time with now (those two factors are probably more important than Caliber).
I do own a S&W full size 9 4.25”. I’m tempted to try to carry that, BUT it is a bigger gun, and it is easier to clip on that shield 45. What’s tempting about it is the length of the grip is just slightly longer than the Shield 45 Extended mag (how I’ve been carrying recently). So, the only real difference that will change with carry is width of the gun and weight with the extra rounds. The gun also feels like a pea shooter after shooting the 45 so much 
. That also being said, it may work its way to being my home defense gun because I think it will be a better option for my wife over my full size 40 with a safety (9mm doesn’t have a safety).
IMHO Biased Opinion, the shield 45 is the best 45 caliber polymer carry gun. It has an extra round than the XDS, they managed to make the gun really thin.