[lerno]

The downside of QBE is that it then requires an assembler and a linker. And QBE's only input and output is still text.

Plus the "frontend -> QBE -> assembler -> binary" process is slower than "frontend -> LLVM -> binary". And LLVM is known for being a fairly slow compiler.

[stevefolta]

The downside of QBE is that it doesn't have a way to generate debug symbols. But I still love and use it.

[YorickPeterse]

The most recent release has the ability to generate basic debugging information (see "new experimental dbgfile and dbgloc directives. " from the release notes) as Hare needed that (and IIRC a Hare contributor added it). Unfortunately, there's no documentation on it, and last I checked to see how to use it I had to go spelunking in the Hare source code.