I am in the process of ordering an arch for Ipanema.  After personally seeing the aluminum arch made by Atlantic Towers, from Lulu and Creamy Puff I was very impressed with the quality,  how light they were, and more importantly by the very affordable price.   However,  both owners (Marc and Mark)  mentioned that the arches were somewhat wobbly, but that was corrected to their satisfaction by adding cables or an extra-strut in a corner.  Although I have seen some very nice arches made to order, their cost , I think, is typically 3 to 4 times that of an Atlantic Tower and they seem to be much heavier.
My questions are for those who have installed arches:
0) if they were from Atlantic Towers, were they wobbly?
For this who installed stainless arches: 
1) do you have an idea of their weight? 
2) how wobbly are they when underway both with and without dink?, 
3) did you have to add extra struts or cables to make them stiffer?
4) What was the cost of manufacture and installation?
5) Can you provide a pix of your system?

Greatly appreciate your feedback
Jose
Ipanema SM2K 278
Still freezing in Boston Harbor but hopefully not for too long.