I have a .40c 2.0 4" and find it to be a pussycat to shoot with 180 gr Blazer Brass and 180 gr Gold Dots. I really like the trigger. The included sleeves for the full-size mags are a nice touch.
I fired a friend's wife's 9c 2.0 4" and I found recoil almost non-existent with her 147 Winchester Defend (Reduced Recoil?) and my preferred Federal +P 135 gr Tactical Bonded. Not sure I could tell the difference. Those +P 135 will get your attention in a LC9S/EC9S so I was surprised at the lack of noticeable difference.
The 3.6 will have more muzzle flip and shorter sight radius. This will reduce shooter accuracy and increase split times for most people. Only you know if the 0.4" will appreciably effect the the way you carry. For me it's a non-issue so I went with the 4.0.
If you don't mind my saying the G48 doesn't really seem directly comparable. The G19-5 seems like the obvious competitor. That said if you have very small hands the G48 makes a great substitute for a Full-Size/Midsize. My lil' Sis uses one as a Game Gun for the local Run&Shoot type events. They require a mag drop so capacity is a non-issue.
I don't think you will be disappointed with either, so buy both!