I'm no expert by any means and I've only very recently gotten the hang of straight razor shaving, but I've been working through the ins and outs of this thing for the better part of three years. In my humble opinion (read: amateur), I find that vintage razors are better than new ones. Here's my rationale:

1) modern straight razors are difficult to judge on quality as they are easily mass-produced from less than optimal materials and are not easily distinguishable from actual quality products. For example: I purchased a new Fromm straight razor three years ago from a barber supply shop under the impression that it was "shave ready". It was not and I have not been able to get it to be "shave ready" despite professional honing and stropping, etc. It turns out that the quality of the steel used in the blade is poor because it is an alloy that just doesn't take an edge that well. It is my belief that metal alloys that have only become available in modern times are used to the exclusion of actual quality steel that takes an edge better. This quality steel is found more commonly in vintage razors because the alloys didn't exist when they were made.

2) Vintage straight razors are often less expensive than modern ones because they are "used", but not ruined.

3) If a razor survives to become "vintage" it usually means that it was effective enough as a razor to be kept around for a long time. Basically, if it was good enough for other people to use, then it is probably good enough for you to use.

Once again, this is just my rather junior opinion and should not represent doctine. As for the "theinvisibleedge", sorry, can't help you, but perhaps other more senior members could weigh in. Good luck with your purchase. As a last caveat, I now own a vintage razor I purchased from the classifieds and it is working better than the new one I purchased for twice the amount.
Best,
Mike