Like you mentioned, DSE and SC&C do offer better geometry. Speedtech's are right up there too. Those are the only control arms out there so far that do offer better geometry. The rest do not (AFAIK
). You had stated that most aftermarket arms offer little to no geometry changes, but there are in fact three that do (and replicate the guldstrand modification).
Not to nit-pick, but you have shown a lack of knowledge of control arms and manufacturing process:
"TIG welding is the best and is always mentioned by the manufaturers of these."
A statement like this, to me, proves that you are not ready to complete this task. I am 90% sure that you say TIG is best is because most aftermarket arms are indeed TIG welded.
But it is not "best". MIG, if done properly, is every bit as good as TIG in this situation. Both processes, if done improperly, can cause failure. So why are most arms welded with TIG? Simple, it looks better. Many, many circle-track arms are MIG welded. It's cheaper and those guys tend not to care about "bling". In fact, one could even say the enlarged radius from the MIG weld bead can offer strength advantages.