hey Gep ... did you email me ???? Hopefully I responded, as we are 100% caught up (Atleast what we have in our inbox!) Shoot me a PM if you haven't seen a response yet.
As far as the RN series 901's (4075's) go. They are programmed to pull about 15% more power than true DSE901's. However, I don't feel this is the case with RN penstyles, as my atomizers have been a favorite of many for months now. Do they eventually die like most other atomizers ... sure do. And I give them the same life span as 901 atomizers, approx 3-4 weeks, before they either go cold or are almost completely burnt out, thus loosing lots of flavor vapor wise. The vapor gets really really hot (although the atomizer may not) and you taste almost nothing ....
I love my RN atomizers ... I have had the choice to move to DSE801's instead, however, I have just never been a fan of them. I have tried all 3 types of 801 atomizers (2/3/4 hole), and nothing compares to the vapor/throat hit I get with RN's. So, for now, I am sticking with RN's