What is he considering it for, I'd ask? CC or a range gun? I've shot one. They shoot fairly well, I feel they're a little more chunky in the grip than many others that I've shot. I've never handled the FNX, but I've shot an FNP9, and it was a nice gun overall. Both the FNP and PX4 were a little thicker and bigger than I wanted to conceal. The SR9 has a fairly thin grip for a double stack, the new triggers are better, and the back strap does adjust some. If he wants real thin grip the PPS, PF9, and the Kahrs are thin. IMO the PPS has a fairly comfortable grip, shooting manners for being so thin. The Kahrs feels awkward to me in the grip, although I've never fired a Kahr. More information on his needs/desires would help us help you more. Certainly shooting as many as he can will help.