more so in terms of reliability and maintenance costs etc.
As mentioned above, I would expect the 330d to be a bit more reliable and cheaper in terms of maintenance compared o the m135i.
330d will be lighter on fuel though.
Performance wise though, from what I have seen is that the m135i will be faster than the 330d and not sure that will change even if you do DP and software on the 330d.
"stage 1" 330d vs stock m135i, I think the 135i is still a bit quicker.
While the N55 engine is great, I have heard a lot more issues with the N55 engine compared to the N57 engine in the 330d.
Seen many 320d's with over 200k KM, a few with over 300k km and even some with over 400k km and with no major maintenance required and I'd imagine the N57 to be able to achieve the same if not better it! Typically speaking of course, there are always exceptions.