Tubular Rim Question

Are most rims a standard 19mm width?
My Tri-Cross came equipped with Alex rims. I don't particularly like them so I built a set of wheels using the Mavic Open Sport rims. The Mavic's are narrower than the Alex, so swapping between them requires brake adjustment. I use them as a pit wheel and fortunately my brake levers have a pin that slides to open the caliper up more so in a pinch I can ride on the Alex wheels, but the lever is opened up more which is not ideal. I'm interested in building up a set of tubbies for racing and want to make sure that the rim I choose will allow me to use my Mavic Open Sports as pit/training wheels without adjustment (Alex wheels go on the fixie salvage project; I know, I know, hipster fixies are uncool). I'm looking at the Mavic Reflex mostly because I have had good luck with Mavic and I'm assuming they'll have identical widths. However, if most rims are a standard width and there's a better rim (especially if it's cheaper/lighter/stronger; I'll take two out of three) than I'd be into exploring other options.

Basically I need to know what tubular rim options I have that have an identical width to my Mavic Open Sports and what you (whoever is taking the time to read this) would recommend. I'm also taking suggestions for hubs (Single Speed, track spacing) and of course, tires.

thanks for the time.