Have you evaluated alternatives such as posits, Kulisch accumulation, and zfp? https://arxiv.org/pdf/1805.08624.pdf https://arxiv.org/pdf/1811.01721.pdf https://insidehpc.com/2018/05/universal-coding-reals-alterna...

In particular the latter describes a generic framework that can be used to generate a lot of different number systems. Could hardware implement this, allowing us to compose and choose the number system by just setting some simple flags?