I've gotta give hax a go, as a pi user who came on-board due to the no frills direction pi takes. I say takes rather than took, because regardless of the (heated) discussion surrounding mcp and code mode support, I cannot fight the numbers- augmenting the harness provided tools is a notable boost to execution round trip performance.
I mostly stuck around with Hax because of a few design choices. The sessions are merely plain text files indexed by a dirpath slug. This means I can just start a hax session in that directory and expect sessions history to be available in any model.. (I occasionally dabble in GLM for security checks, Gemini for writing stuff, Deepseek for tightly scoped tests etc).