Agreed AEM7AC, yes newer diesel engines in general may not sound as "pleasurable" to the ear to rail fans as older ones, simply because they are used to hearing the older stuff. For example, many foamers would much rather hear a GP40 or SD40-2 than a GEVO or Dash 9/AC4400. However alot of crews prefer the comfort, quietness, power, and reliability of newer GEs vs older EMDs, so it is another one of those railroader/foamer perspective conflicts.
Although there have been a few cases such as 1123's smoker HEP and 1132's fire in North Station, the CAT C-18 HEP generators have been very reliable, and don't sound too different from the older ones, IMHO. If anything, the CAT 3412s in the rebuilds have had more of their shares of problems!..
MBTA 1051