a) Time and manpower to do all the "to do items".
No, certainly, I agree. It's a massive project, and it's really astonishing how far they got. I certainly do not disagree with this.
b) Gunnar/the team wants hardware that runs alot/most of the software available, BUT at the same time opens up for future developments on the software side. Making sure the FPU for example has functionalities beyond what was the norm in the 90s.
Well... The disagreement is probably a bit what the "future" should be. For example, from a purely technical perspective, I understand that Gunnar wants to opt for a 64 (double precision) FPU only because it is readily available as an existing functional block on some FPGAs, but this also has the risk that it may potentially cause compatibility issues with existing software that may possibly depend on 96 bits. So it's a sacrifise to make. I personally disagree with this choice and I'd rather have a slower, but fully compatible FPU. That's basically because I believe that the times AmigaOs or Amiga would have had a "future" are long gone. Most people use it as a legacy system for "good times", but not as a productivity machine.
And is it unrealistic that the Apollo Core FPU will be able to deliver the legacy functionality? Be it thru its internals or thru library support?
It wouldn't be a hard problem to provide a mathieeedoubbas & friends that works with the new FPU, that's an easy problem to solve. However, this still doesn't make the FPU full 96 bit, and I am a bit afraid that *this* may *potentially* cause some problem here and there. But then again, a FPU is really rarely needed, and number crunching is not exactly the application domain of the Amiga - so one doesn't neither a *fast* FPU, nor a *precise* FPU. The current state as far as the FPU is concerned is therefore not as bad as some people want to make it appear.
There is the issue that in the future there might be programs released that works exclusivly on the Vampire, and I guess thats one of the main sources of annoyance/worry from some people.
Well, I don't even know whether this really worries me so much. Having a fully compatible working Amiga system would certainly be nice, given that the hardware aged. The problem is more that the Amiga environment depends a lot on its legacy software, and I don't believe that intentionally introducing an incompatibility "for the sake of speed" is a good move. I would put compatibility first, and speed second. After all, if I want speed without compatibility, I already have a PC, and the new core will still not be powerful enough for any real-world applications in first place, so why bother too much about speed in first place. Speed is nice, but compatibility is a "must have", and speed will come with new FPGA generations anyhow.
Unfortunately, this vision is not quite shared by the team, and that's probably the main issue. One could have done things "right" with a potentially slower full FPU, and a potentially slower full MMU, no matter about the details too much, but "complete enough" to do anything a 68K can (or could) do.