Back to the OP:
I find that I cannot support this sort of thing ( which I do not support in principle, anyway ) mainly because of the 4 main groups that are in the alliance...
Anglicans, Baptists, Reformed and Presbyterian.
Many truths of the Bible that I hold dear are not supported by even 2 of these 4 groups,
and none of them is, in my estimation, without grave error in some of their doctrines and / or teachings.
Some teach infant baptism ( even for those who are children of believing parents, like Presbyterians do ) which is reserved for believers alone...
Not unbelievers who have never confessed Christ as Lord and Saviour.
Anglicans have their own set of problems, IMO, such as affirming or ordaining those who disobey the Lord's commands in matters of sexuality.
some Presbyterians also ordain women pastors, which is not in accord with the Scriptures.
As far as I know,
both Presbyterians and Reformed teach amillennialism, which is also, in my studied opinion, a grave error.
The one thing in common that I am in agreement with them,
is their ( apparent ) stand on God's sovereign grace...
which most nowadays hate with a vengeance and brand as "Calvinism".
They and I would stand on that as a common ground...
But, regrettably, there are far too many other issues that I know would come to the surface,
and that I would and should break fellowship over them with.