It's somewhere in between sky falling and no need to panic. Ever since there has been fuel injection on cars sensors have told it what to do.
Anything that is new technology, and this applies to Tier 4 as it did to Tier 2, 3 etc. gets the bugs worked out in the field. That means the end user pays for the bug fixes, or retrofits, until whatever it is works as intended.
Sometimes things get done during the manufacturers warranty, and sometimes during the EPA's separate emissions warranty timeframe. Either way, we as consumers pay more for the mandated technology at retail purchase, and possible down time when sensors and other items are bolted to our tractors, cars, trucks. Our time is valuable but not accounted for, and we are the guinea pigs for the government's debugging of our equipment, ultimately at our own expense in time/profits lost, loss of peace of mind, and higher prices of additional filters, and more fuel burned to do less actual work.
It's otherwise great because the government told us we need it because.... Embrace it, but not too tightly, you might get burned.:confused3: