You will have increased chassis maintenance expenses - air brakes that need service, more oil for the engine, the transmission should have Transyn synthetic fluid which is very expensive, more coolant (it's important to keep the additives at their proper level), axle fluids, a huge air filter to replace periodically, etc, etc.
We have the Cummins ISL (1200 ft. lbs and 400 HP) and it seems like everything on our chassis takes 26 quarts of fluid - engine oil, coolant, tranny, axles, coolant, you name it.
We just had the major Freightliner M3 service done and it was $1400 which included gen set service. It was about $200 more than the usual M3 due to being time for new Transyn fluid in the Allison 3000MH.
Not to scare you, I've never regretted for one second our ownership experience, just be aware of maintenance expenses.
Oh, one more thing - take good care of your chassis and it won't let you down