Of the two red dots you mention, I prefer the SRO. The SRO has a bigger window and I like bigger dots. The SRO comes in a 2.5MOA and a 5MOA red dot. I run the 5MOA. The 507C you reference has a 2MOA red dot or gives you the option of a circle-dot reticle (2MOA in the center and 32 MOA ring around it). For me, the circle-dot is too confusing having shot 5 to 6MOA red dots on multiple guns for a long time, and the 2MOA dot is a tad small for fast pistol shooting. Yes you can bump the brightness of the 2MOA up to make it more visible but there’s a limit to how much you can bump it up in full sunlight and when you increase the brightness the crispness of the dot is blurred out. The two Holosun’s I have are the 407K (6MOA dot) and the 407CO (8MOA circle). The HS I want to get is the 508T but not until they come out with a 6MOA reticle.
The HS window is a little smaller than the SRO, both have batteries that can be accessed without taking the sight off (unlike the original Trijicon RMR). Both have big +/- buttons for adjusting brightness. Both share the same mounting footprint which is a plus. Trijicon’s customer service is pretty good. One of my SROs died on me after three year of match shooting and Trij took care of me with no questions asked -they just sent a RMA for repair and received it back in about 5 weeks. I have yet to test Holosun’s warranty but hear it is also decent.
