Wow, that turned out nice!
On the legs not being as rigid as you hoped, the pic looks like about the same surface area under the lathe feet as the old Logan lathes. Of course, those were cast and had virtually no 'give' at all. Also a heavier material (thicker). But the older legs also had that curvy art-deco look. So the feet were broader apart front/back, and also sat a few inches outside, compared to where they connected up to the feet of the lathe bed. A bigger footprint so to speak, like an a-frame.
Bracing ought to cure any movement in the stand. So just my ramblings on machine stands.