I find it more 'natural'. I think the reason for this is that it forces you to stick your butt out properly (and if you aren't doing that, you are about to visit snap city).
What most people don't remember, is that your lower back (whole back, but let's say lower for the sake of discussion) and your hamstrings are fighting for control of the pelvis. And the back absolutely must win. If it loses, then you get flexion, a trip to snap city if you're lucky, and if you're not then it's a trip to busted out up city. Deficits will force you to tighten and hold your lower back, push yout butt out, get a better hamstring stretch and flexibility and the this carries over to conventional
In a nutshell, they;
a) expose any weakness your form has
b) force you to correct it
c) improve your positioning and form for conventional
d) absolutely improve your leg drive
e) have that improved leg drive carry over to your conventional
f) improve the most important part of the lift; break and rise
I'm not 100% that doing them all the time is the way to go. They definitely apply more tension across your lower back, and this is unavoidable (just as squatting 6 inches down vs full ROM will place different strain on the back, knees etc.)
If you're tall and have the gorilla length arms that come with it, then conventional is perfect for you anyway. If you have ridiculously long legs and shorter arms, then sumo is where you want to be. Given every law of the universe, the vast majority of us fall into 'average', and will be fine at either without particular leverage advantages. And deficits are what enable you and me to get more for our 'average' buck.
The other danger with deficits, is that they're approaching squat-ville. Not a bad thing per se, and you shouldn't change the way you lift, but it will unquestionably impact your squat form and quad recovery. OWL - less impact, other than the impact that affecting heavily used muscles even further will have. But squats will be affected something fierce if you're doing them properly (deficits and squats both).
