The issue with any switchable 4/8 way stick is that they usually need to have a square restrictor which rotates to diamond for 4-way play. The relative size of the restrictor and actuator, and the switch position, is a very delicate balancing act which the designer must perform. Even when these are ideal, there are limitations which can't be overcome. As indicated above, good 4-way sticks are physically restricted, and have a short, quick actuation. Even the best switchable will have a longer throw in 4-way, than in 8-way, thus the shorter one tries to make the throw in 4-way, the more truncated the 8-way throw becomes.
Switchable joysticks, either physically or digitally, are a compromise. The laws of geometry and physics pretty much dictate that a joystick which can do both, will do neither extremely well, or do one well at the expense of the other. They do have a place on many a panel, but expectations need to be measured by what is actually possible, given those limitations.
All that being said, a very good "do-all" stick is possible. But it would require a fairly complicated mechanical contraption, coupled with some digital technologies, to pull it off. By time one considers the cost, possible reliability issues and complexities of use, it would probably make more sense, for those looking for the best possible performance, to plant a proper 4-way joystick on the panel somewhere.