That is a loaded question! Here is my nutshell version
Are you looking to add to a layer flock or a breeding program for resale?
If you just want some gorgeous productive green egg layers for a laying flock, then there are several breeders with 2nd (or 1st) import stock that can fill the bill. Just be diligent in your search to make sure they really do lay green eggs.
As a breeder, if you are looking for rare breeds that you can put in a pen and be ready to go, Isbars are not what you are looking for. They are definitely a work in progress.
The 1st import stock is much more uniform in appearance than the 2nd import stock. IMO, the 1st import stock is much closer to the foundation stock in Sweden than most of the 2nd import stock. This impression is backed up by my breeder friends in Sweden. However, the 1st import did, and a few still do, suffer from genetic issues due to inbreeding. Most of the breeders that still have the 1st import (myself included) have worked very hard on diversity to make the remaining stock healthy and vital. Brown egg layers, though still relatively rare in the population, are much more prevalent in the second import than the first. The 2nd import stock has a much higher percentage of undesirable characteristics (small, hybrid-looking combs, lighter eyes, feathered shanks, mottling, red/copper in the hackles and saddles and stockier body-type just to name a few). Most people that have both imports much prefer the first (myself included), but I do know of at least one dissenting opinion. Those breeders I have spoken to that had good 1st import stock but added 2nd import to it for diversity have for the most part regretted it.
I have stock from both imports. I have a cock and 6 hens that are all 1st import (from 3 different sources) and I have 2 second import hens directly from GFF and a trio of mixed line birds from another breeder. I will be adding stock this spring from other breeders that have pure 1st import stock, but I will not be adding anymore 2nd import stock to my breeding program... ever. My plans for the second import stock that I already have are to keep breeding it back to the 1st import lines to improve it so that it can eventually add more diversity to the main breeding program.
That said, there is a lot more 2nd import stock out there to be had. Some of it is good, some of it is not. To me, some of the 2nd import stock shows influences from Marans and Araucanas, neither of which were used in their creation.* IMO, you need to be very picky about who you buy your 2nd import stock from. They must have good stock to begin with, know what they are breeding toward, and also know what characteristics they need to breed out. The latter two are the real kickers now. Up until about 9 months ago, there was very little information available about the Isbar - basically just what was found on GFF's website. There is no SOP for the Isbar, either here or in Sweden. A lot of breeders take this to mean that basically anything goes. And many who bought 2nd import Isbars just assumed what they got were good examples of the breed and set about breeding and selling them. However, there is a description of what the Isbar should be imbedded in the foundation stock in Sweden. It is just not written down in an official description yet.
About 9 months ago, I got in touch with a few individuals from Sweden who are involved in the preservation program over there. They joined my FB page and the true information about the Isbar has been flowing in a steady stream thanks to their help. We are learning what the Isbar is supposed to be and what characteristics are not desirable. But many Isbar breeders are not yet aware of the information that is available there and still breed blindly. Because there is no official easy-to-access SOP, even many that are aware of the information have not read all that is there and made use of it. (I am working on a synopsis to post in an article here, but I haven't had time to finish it. )
Can you make a good breeding program from just the 2nd import stock? I believe you can, but it will be a long road requiring a lot of research and diligent culling on your part. The 1st import stock will still require much research to know how to breed well, but the road to good breeding stock will probably be a little shorter and less frustrating. Either way, you are going to want to obtain stock from at least 2, preferably 3, different sources to ensure good diversity. I would suggest at least one of those sources has a good percentage of the 1st import stock.
* While looking back through the Isbar thread recently (http://www.backyardchickens.com/t/535731/isbar-thread/0_20, in post #4), a member from Sweden talks about the difficulty finding pure Isbars as many breeders there had bred them to Araucanas to "improve" egg color. So I guess what I am seeing in the second imports is not just my imagination.