What most people forget is that in a regulated mod, the lower the battery voltage, the higher the current draw. Your calculations are also incorrect as you're assuming a 100% efficiency, which is impossible. ProVape have stated the P3 has a 95% efficiency rating, which is very high.
With modern LiMn batteries you can easily do 60+w safely.
That's a loaded statement (pun intended). There are plenty of "modern" LiMn cells coming from China that can't handle 20W safely. However, if you're talking about a very good name brand like LG, Sony, Samsung, etc., they're "safe" up to about 60W, but not more. At 60W, with a 3.3V low battery cutoff, 20A is being drawn from the battery - the maximum for most very good name brands. Sure, a couple claim 25A, so you could go beyond 60W, and it depends on the manufacturer's definition of "pulse", but you said "safely" and I disagree with that.
And by looks at this mod, it could realistically be a dual 18650 mod, or even a LiPo mod, which would safely handle the 120-200w range.
Again, 120W would be a safe limit for a dual 18650 or 2S LiPo. That's why the DNA200 allows you to use dual 18650's but limits the maximum wattage to 133W (and IIRC 100W with the SX-based dual 18650 Vapor Flask), not 200. That's also why you have to use either 3x 18650's or a 3S LiPo.
PS - Sorry AstroTurf, but the 40W number is meaningless as well.
I'd be surprised to see much over 30W from ProVape from a single 18650, and doubt they'd go over 40W with a dual 18490, which is what the Radius looks like to me.