i am in the same boat. looking at the m235 while i run my 335 ive had for 4yrs. i still love my 335 so im in no hurry. the 235 wont be out until nov so theres plently of time and I dont want to be the first one to own it. i usually like to wait a bit to see how things shake out. plus I want to see how the m2 pans out before I make my decision so im ok waiting 2yrs or so.
ps. there are plenty of 335s over 100k going strong. plenty of threads on it, just search. the are common points of failure, but the biggest ticket item is the turbos. ive had mine replaced so i should be good for a while.