Did you buy two?
I get it that the Seaskin is economical. But when I have the option, I prefer to deal in-person with a business I am buying something from that needs to be custom measured and will likely need service at some point. They know me. They have my suit's service records. It has been my experience when dealing remotely with someone that they don't prioritize you as they would if you were face to face. When my boots needed replacing, the guy from EE and I marched over to Santi USA in five minutes so I could try on boots. As I see it, what I'm paying for when I buy Santi at the (US) source is almost less the product than the guarantee that they will do whatever it takes to make everything just right. As a mail-order customer to some business, I am just another number to them. I suppose I am just gun-shy after having experienced too many headaches dealing with companies by email and phone, trying to get things sorted. Granted, dealing in person with a top drysuit dive shop like EE or DRIS is not feasible for every diver.
I did. Not at the same time. As someone on somewhat the "pioneering" end of purchasing from Seaskin, I only bought one to start. I received my second last month.
I totally get what you are saying about paying extra for service. If the actual Santi factory were near me, I would have given a lot more consideration to buying from them. Being able to let THEM take the measurements, and then trying it on there, so they can immediately fix it if it does not fit right is worth something. Once it's made and verified to fit and work correctly (i.e. not leak), the service after that is, to me, no longer so much of an issue. There are plenty of places to get a suit worked on that do a good job. DRiS did great work on my Waterproof suit. I hear great things about Gamble's, down in FL. If the suit fits right and has no other fundamental flaws, after that it's just not rocket surgery.
Getting it right on the front end is, to me, the most important thing. And that is where Santi does not seem to have any advantage over Seaskin. And perhaps even a disadvantage. To anyone in the US, Santi is no closer than Seaskin. Further, I have not seen anyone post about a Seaskin suit that was totally wrong. Minor details, yes, a couple of reports (though my 2 suits are perfect, so far). But, a suit that, for example, simply does not fit? I haven't heard of that with Seaskin.
On the other hand, one of my friends ordered a made-to-measure Santi heated undersuit. It arrived and fit perfectly (thus confirming that the measurements he gave were correct). But, his DUI drysuit would not fit over it. Obviously, that's no fault of DUI or Santi. So, my friend ordered a Santi drysuit to fit over the Santi heated undersuit. He requested it to be made using the same measurements. It arrived and was simply too small/tight for him to wear. The notion that you mentioned of "they will do whatever it takes to make everything just right" is now the topic.
Once the drysuit was confirmed to not fit, Santi fought tooth and nail that it was their fault. Even though they'd made the undersuit using the same measurements and it fit perfectly. Ultimately, my friend had to go get re-measured, on video, so the Santi people could watch and confirm the measurements were done correctly. Only after that would they admit that the measurements were correct and they'd made the suit wrong.
Seaskin seems to have a much more modern production process that helps to make them much less likely to have that kind of problem.