If you look inside a mech like the REO Grand, you'd see that there are no wires. Its all metal parts making contact and carrying the current. If anything breaks its a fairly simple job to replace those parts. A regulated mod is going to have the chip and wires. The electronics and wires mean more possible points of failure: soldering points, a bad board, worn out wires, ejuice getting onto the parts (especially for squonkers). That makes them more fragile, and more likely to break in case of drops as well. And if it does die, it would be a major pain to trouble shoot the device. Hence the idea that regulated mods won't last as long as mechanicals.
If you look through the VV/VW thread, you'll see people complaining that their regulated mod died on them. Having said that, I havent had it happen to me personally in 4 years of vaping, except for one DNA40, but that was notorious for having a bunch of bad boards. Overall though, I'd say regulated mods have been improving a lot recently. My experience has been pretty good (knock on wood).
A for the DNA 200, I dont think that chip has been out long enough to judge longevity. There aren't a whole lot of modders that are making squonkers either, as far as I know. Because of the Lipo battery and the bottle, they tend to be bigger than the usual squionkers too. Catfish Atty mods is making a DNA 200 thats only slight larger than a Sunbox so that might be your best bet. You can find Tom here
Catfish Atty Mods Chapter 3
Personally, I don't vape much beyond 50w so I'm fine with a vtc mini chip if it means being able to replace the batteries on the go. Now a 133w DNA200 with 2 18650s, shaped like a Reuleaux would be a great compromise for me. YMMV.