1. what have you tried pesonally - and which model flute
Too many to list.
2. the grenadilla headjoint shuffle - interperate it how you want - just give me your gut feelings
Wood alters the overall tone of the flute. But it's still a flute and the change is consistent throughout the instrument's range. That said, many wooden headjoints are poorly made and finished and lack the responsiveness of metal ones. They also play differently due to moisture levels and need to be oiled and maintained properly lest the bore gets out of round. (note - this affects oboes, clarinets, and so on as well)
A 30 year old metal headjoint will still play like it did when it was new because nothing changed. (well, maybe replace the cork in the tuning assembly)
3. modern cut vs Baroque etc
Makes no difference, really. Alters the sound a bit, but since every maker is so different from each other, one modern might sound worse than a baroque or vice-versa. In fact, sometimes headjoints of the same exact type sound or play drastically different.
4. Colour and projection - how the embouchure hole is sculpted
5. Lip riser metals - is platinum the mecca of sound
These are the same. I've heard handmade Haynes headjoints that weren't as good as a handmade Yamaha. It's all about the skill of the individual who made the head joint and you really have to try several yourself as some are junk, no matter what they are made out of. Some are also fantastic even though they are made out of rather mundane materials. (though generally handmade does beat machine-made, of course)
6. alternate flute metals and material -
This makes zero real effect on the sound if it's the same general type of material. ie, metal is metal. Wood is wood, plastic is plastic. But it's an overall tone to the flute and not anything you can control or change. So your audience won't tell any difference unless you do a back to back comparison. Then they might say "they're different" but not be able to tell you why. Comparing drum heads or cymbal brands would be similar. The listener won't know the difference between two brands, or even care.
If the body on a basic Powell didn't play in tune as well as their top model, they'd go out of business rather quickly. So generally, it's more of a maker vs maker difference as opposed to what it's made out of. Yamaha, for instance, has a specific scale and tuning. Powell has a slightly different one. But between the models, the headjoint and features, as well as the construction differences are what's key.
This of course can save you a ton of money. A pro headjoint plus a good mid-range body can be had for under $2000 quite easily. And sound like the $10K flutes.