I'm not sure what you mean by 'conventional', but I'm going to assume that you are referring to a package unit since we are talking manufactured homes here. Also, since I don't know the premise of your question, I can only partially answer.
Conventional (package unit):
Advantages
- low operating noise level (inside)
- self-contained
Disadvantages
- duct heat loss/gain
- critters & strays can tear them up
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Split System:
Advantages
Disadvantages
- higher operating noise level