Actually using ZLIB might not be the best idea, better would be something that's faster.
I'd go with LZ4. There's also lzturbo, but, lz4 has format that might be nicer for "small devices" (raspis & Co.)
And ChuckOne is right, binary protocol equals problems
Compression looks like a premature optimization to me. Let's make things more complicated when we actually need it.
Isn't maintaining two protocols making things more complicated?
Using a binary protocol looks to me like a premature optimization because you sacrifice all the advantages of a text-based protocol and buy in pitfalls. Just because you want to have more TPS although the current way is much faster than Bitcoin itself.
Anyway, I think you have heard the opinions from some guys that are from the industry knowing the problems with binary protocols.
How you are going to appreciate that experience remains to be seen. Regardless which way you decide, please always choose the most secure one. And remember: nobody's perfect, especially not programmers.
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