The 335i's have had some issues... Not the extent that some of ridiculous prior postings. If you're buying used, look for one owner, maintenance records and try for a CPO (BMW certified pre-owned). N54 had more issues than the N55. Common are fuel pumps, waste gates and injectors. A CPO will cover all of those parts. I haven't heard of any double clutch trans issues. BMW transmissions are far superior to Nissan's. Do some research
If you have the extra coin... Pick up an E90 or E92 M3 with the gas guzzler s65 engine. Consumer reports rated it the second most reliable sports car last year. However... The wife's car will then out-perform your car in ever category, including sitting in the garage. The DCT in the M3 is insanely fast and can easily be tuned for even better performance.
Good luck OP!