You are right that it is not difficult to maintain the trim on jacket BC, but it is generally significantly easier to do so in BP/W.To maintain a horizontal trim is NOT that difficult with jacket style bc.
Too many divers are carrying more than necessary additional weight in one place especially around the waist.
DGX BP/Wset up is very good and really do not see the point to purchase an travel bc for travelling.
Your money your choice.