The main issue is that with a standing alarm you do not know when another alarm comes in, and to check what it is. I have heard in the past that TT did not connect the CEL, so one would not know what was happening. I realize when you rig is running good the CEL and OBD2 port are irrelevant, but when thing start going wrong without notifications it can quickly end a trip/vacation.
I would suggest that you get a wireless OBD2 reader and App that you can run on your phone to keep an eye on what alarms are coming in. (I got mine off Amazon and are under $20.) If you do not have an OBD2 port, you only need four wires to make it work, and I suggest that you do that.
The Hp & Torque makes this a fun swap.