I think the max guide number in meters might be a misprint. The max GN in feet is 169.9, which translates to about 52m.
The Canon USA specifications section states, "The maximum Guide No. is approximately 196.9 ft./60m at ISO 100 and 200mm flash coverage." Canon EU lists GN 60 m. So, I'm pretty sure the 169.9 ft GN is a misprint – whoever wrote the intro paragraph for the Canon USA page just transposed 196.9 to 169.9.
Same master capabilities for radio. If you're like me, with a few old optical only flashes though, makes an upgrade a little tougher.
I did have a shoot (in the family, I'm not a pro,) recently where I was using high speed fill flash and cycle time on my old 580ex was really a limitation. Missed several shots because of it, and the EL-1 is out of my budget, so this one is looking interesting..
If you really need to integrate an older, optically triggered Speedlite into an RT setup you can use a
Sonia Green optical trigger, although that requires manual mode (no E-TTL pre flash). I use the built-in optical trigger on my PCB Einstein monolight and it works fine (I had the PocketWizard MC2 radio for that, but the whole MiniTT1/TT5/MC2 setup was kludgy, and I have been much happier with Canon's RT system).
The rapid-fire of the EL-5 will be nice for on-camera flash. With off-camera, I've never needed to trigger that fast as those are more controlled setups for me (studio portraits).
I'm curious to try out the Custom Flash settings linked to C1/C2/C3 on the camera. Nice to see features like that enabled by the multifunction shoe.
Even more useful for me (and another improvement over the EL-1) is the menu direct button on the EL-5, where one press brings up the flash control settings on the camera LCD. The ST-E10 has it, and it's very convenient for me since I find it easier to control flash group settings via the camera (though like the EL-1, the EL-5 also has a more useful display that mimics the camera flash control screens).
Looks like March 30, 2023 is the expected delivery date for the EL-5.