I'm considering custom work on a 640-1. Among other things I'm thinking about replacing the stock front ramp sight. The gunsmith is recommending an XS Big Dot. I've never seen one outside of pictures. Not sure it's the way I want to go but not totally opposed either. Usually I prefer something more like a Patridge sight. Searching P-F most of what I'm finding is anti-big dot but is mostly in context of Glocks or shotguns. What's the running thoughts on them for J frames? What other options do folks like?