For our 2 RVs with slides: Advantage is more space.
Disadvantages: More cost and maintenance (seals, toppers, equipment to move slides, etc.). Narrow or restricted sites for slide deployment and/or less room outside. Our rigs have basement storage under the slides and the access is more restricted when the slides are extended. Restricted inside access with the slides in like cabinets, beds and some even report bathrooms.
OP and others: Always check all inside and outside access both inside and out before any purchase. What about access at a rest stop? What about access on a street when the street side slides cannot be extended or even trees on the curb side. And we park at a family house where turning the RV around is not allowed.
The advantages for us outweigh the disadvantages. :)
