Chaz, I am not sure of your question. Are you saying you want a ScrewDriver and which one is best OR are you saying that you are not happy with your 901 penstyle?
If you want a screwdriver with 901 atomizers, I suggest the MKII at Totally Wicked. If you want to to try the original, then try the MKI and I suggest the 510 atty connecter. The MKI is smaller in weight & size and is avail in 510,901,or 801 atty connectors. Stay away from copies like the 905 IMO.
I have both ScrewDriver MKI w/ a 510 atty and a MKII with a 901 atty. I use the 510 mostly. I got an adapter for my MKII so I can use 510's on it. OBviously I like the 510 atty better then the 901. Also, I recently discovered the *new* 510 cartomizers @ litecig (and others), and I have what I like the best now. I am using a 510 MKI ScrewDriver with 510 cartomizers. Frigging awesome and a cartomizer is lasting me about 4-6 hours of heavy vaping after a fresh fill. I go through 2 batteries and 2 to 3 cartos a day.