The pictures for the home told me enough, but there weren't that many clear pictures. It was hard to tell from their advert photos how good the textures were, but retexturing prims is much easier than mesh, What was important to me was the shape of the building, and how I could see how it would fit on the parcel. The size of the rooms themselves aren't so important to me, and the limitation if you are modifying a building is really more the parcel than the building itself.. Also what goes on in my bedroom is probably left private so I bought a 5 land impact mesh skybox for 15 Linden dollars which works perfectly for me. Again with that I never bothered to look to demo it. I could see enough from the two pictures in the advert that it should suit my needs. With the addition of some prim walls it has a bedroom, bathroom & kitchen\diner lounge with one of those windows with a view just behind it.
I didn't know the convex hull trick would work so well on the beach house, I wasn't banking on that when I bought it, infact I am surprised the builder hadn't already used it. Basically by setting the physics shapes of linked prims to convex hull it forces them to be counted as if they were mesh so for simple prims it halves the land impact. Any sculpties are best removed from the linkset and added to their own so they don't get counted as mesh.
For small parcels in awkward shapes like you get on mainland modifying a building is really the best way to go about it. I spent quite some time looking on Marketplace trying to avoid getting my hands dirty doing a rebuild... but there really wasn't any other option, and I am so pleased I did.