Thanks everyone for tips/experiences!
ACR definitely looks like a company I should add to my list. Their combo of mirror and whistle looks great(I guess this is what you described, Nomad -
http://www.acrelectronics.com/hotshot/hotshot.html ). It has also a cylindrical float so it doesn´t sink.
sometimes a smaller one with you counts more than best but in the pack someplace else
You are right, ironraven. I should replace StarFlash Ultra on my list with the smaller and lighter StarFlash.
I have created a small comparative list of the mirrors I am interested in regarding size, weight and the ability to float.
StarFlash (Ultimate Survival)Size: 2" x 3" (5.1 x 7.6 cm)
Weight: 0.7 oz (19.9g)
floats
Hot Shot + whistle (ACR)Size: 4.25 x 2.75 x .19 in. (10.8 x 7.0 W x .5 cm)
Weight: 1.8 oz (51 g)
floats
Rescue Flash (AMK)SIZE: 3” tall x 2” wide (7.62 x 5.08 cm)
WEIGHT: 0.32 oz (9.1 g)
doesn´t float
Rescue Flash from AMK looks like a very small and lightweight mirror, exactly for EDC. It doesn´t float but I could make some small float for it. Hot Shot should be lighter since I believe 51 g is the weight of the whole combo.
As for whistle after further research I really started to like the ACR one. Thanks for suggesting it.