Lets just point out the differences to get an idea:
1) Current Kitchen + Dining room will have to fit in a Dine-in Kitchen.
2) Current Big Living Room + Big Den will have to fit in Small Living Room
3) All the crap in the shed will have to fit in... oh well, no shed.
4) Stuff in carport will have to fit in a side porch half the size.
Now the good things.
1) One and a half bathrooms will become 2 full bathrooms. No more kid fight about who takes a shower first, they can both go in.
2) Closer to kids school and just 300 meters away from kids daycare.
3) Cheaper by 20%.
Definitely some crap will have to go on yard sale or get tossed. But with great organizational skills and smart space usage, it should work just fine.
On another thought. The savings is not gonna be just the rent. A smaller place is easier to cool down or heat up. I expect the energy bill to be a lot lower.