I stopped using 3pc models period, although when I did I preferred the taste and hit of the m401 over my 510, I never understood all the 510 fans. In my opinion it was crap, a poor design that one had to play with and mod before enjoying the experience of using it. The carts don't last long and I don't want to spend all day fiddling with something every time I wanted to vape. When you get tired of playing around check out the KR808D-1 or better yet the GreenCig and you will be putting those 510's in a drawer or away to friends and strangers. The last mod that I bought is the JuiceBox mod by Carlos which is also a vaping machine. If your into the big battery mod I suggest you check out the reviews on here. There are a few up in the review section, I love mine and I have not had to change my juice in over a week now.
Already tried the 808, It's what made me decide to go back to my 510's. But like others are saying... it's different strokes for different folks... I'm glad you found something you like.