My 2 cents worth:
Inside Line did a lame job on this one. First clue was the sticker price BS.
The 335is has a niche, similar to the beloved E46 ZHP. Yes you can save some $ by opting for a N55 Msport. But if you are serious about performance the N54 with extra cooling and lighter flywheel has some big advantages. If you do not want to tune and mod and change exhausts etc. then the 335is is a lot more fun out of the box with full warranty.
If you need 4 doors (E90) then it's moot.
M3s are great, always have been. But never has there been the option to mod the little brother into a M3 killer like with the N54.
I find posts that suggest the M has some mythical powers to be pretty lame. The formula is fairly simple. What distinguishes the M is the high revving V8 and an integrated package of LSD and aluminum suspension bits. In Euro the V8 is great. In the USA you are looking at a lot of speeding tickets to exact much fun out of it.
In a test drive I find myself enraptured by the M. But who did I marry? The 335.
The biggest complaint I have regarding the current M3 is weight. As a performance car, it should be significantly lighter than the daily driver 335. That is why I am so excited about the Z2M. If it comes in under 1000kilos / 2250 lbs., it will be the most fun to drive car ever.