I have assembled all three of the HGA kits (Silver Solution, Super Silver, and Silver Lace). The Silver Solution and Super Silver are fairly easy to assemble and solder, because they have relatively few strands. As Drrasta noted above, the Silver Lace is a bit more difficult, since there are 8 strands in the braid, and you have to have a voltmeter/multimeter to determine which 4 strands are positive and which 4 are negative. Once that is done, however, the soldering is fairly straightforward. I took me about 2 hours to assemble and solder both pieces of the Silver Lace cable. If you have a decent soldering pen (and a voltmeter in the case of the Silver Lace IC's), and don't mind spending some time doing the assembly, I think the kits are a great buy. If you do NOT have a good soldering pen (and voltmeter), the extra cost to buy it may largely offset the cost savings on the kits vs. factory assembled units.
I am using the Silver Lace IC's between the preamp and the 2 power amps, and Super Silver IC's for all of the connections between the various analog components and the preamp. I am very pleased with the quality of HGA's materials and RCA jacks, and think that both of these IC's represent excellent value. After I installed the IC's in my system, I noticed subtle but positive improvements in the sound quality -- smoother, cleaner highs, and a slight improvement in bass reproduction. I honestly can't say that I hear consistent differences between the Silver Lace and the Super Silver IC's, but I have not done a rigorous A/B comparison (switching back and forth between IC's is more hassle than I'm interested in).
I bought the Silver Lace cables for the preamp to power amp connection, rather than the Super Silver, because the runs are a bit longer (2 meters vs. 1 and 0.5 meters for the other components), and I wanted more strands in the cable to be sure the signal transfer from preamp to power amp was as accurate as possible. (To be entirely truthful, you may find in your system that the Super Silvers work just fine, and the Silver Lace IC is overkill. I suspect that it will depend on how good your system is, and how much audio paranoia you suffer from -- the audiophile's secret worry that somewhere there may be something better that you are missing out on.)
There are other regulars on this board, such as Trelja, who have the Silver Lace IC's, and they may also have comments to offer.