There are no drawbacks to separating the real estate and business into separate LLCs that I’m aware of. Every attorney I’ve ever spoken with agrees on this. Real estate should never be held inside an S corporation or LLC treated as such. Any tax negatives are easily resolved with elections.
The issues involved with combining real estate and a business under an S corporation are many. Legally you limit your option and put asserts unnecessarily at risk. The tax problems are hard or impossible to resolve without inflicting additional tax pain.
Structured properly your business and assets can enjoy legal protections while basking in the light of lower taxes.