Half the point in building a bike (at least for me) is to build one with geometry which suits my liking/riding.
And for a race road bike - it would (in my opinion) be ok with low stack, and a more aggressive positioning. But for anything else - leasure rides, communting, or a bit harsher terrain i think it is always better to have a bit more relaxed position - doesnt give neck problems in the long run, and better control in rowdy terrain. Actually for gravelbike in general i think ultra low stack is never needed.
The same applies to headtube angle - that is also to personal liking... i think 71-72 is great for the type of riding i like and mostly do - if you go harsher terrain i understand you go down to maybe 70. If more than that is needed, we are into MTB territory imo.
This is just my opinion, nothing else. And as said, stack is always fixable with spacers - but i would rather look at another frame with more stack.
Both frames does have it's positives and drawbacks - but for me, GV201 does have the biggest drawbacks of the two.
lidation who started the thread asked for opinions, and the above are my opinions.
I like that there are low stack frames like Tidace, for 2 main reasons:
I'm 1.70, but but short legs and long torso. So, I need the stack to be as low as possible. Anything above 530 is too much for me.
Also, I race gravel, an some races are most like road races than really rough terrain. Aero is a must.
Currently I race a Van Rysel RCX, but the limitation of 40mm tires and high stack send me to the search for a new frame.