Came across this thread while doing some searching and figured I'd register to leave my .02. I have never used swankherb.com before, but took a look around and noticed I'd used a few of the products listed, so thought I'd leave a quick review. First, I wanted to second what SlowSpyder said, jwh is structurally nothing at all like THC. The only similarity at all is that they both act on the same receptors of the brain.
Serenity Now: Have tried the blueberry variety quite a few times. The flavor gets old fairly fast, but the high is really good, espeically if you don't have any jwh experience. It rolls well, but creates a lot of resin, so if you're using glass, be prepared to have to clean your glass screen out a lot.
Fire N Ice: Very potent, and a pleasant herbal flavor, will leave you high and happy for a solid couple of hours, followed by lingering chill for a couple more. Nothing bad at all to say about it, it's my preference, especially if I have stuff to do and need to be coherent.
Dragon Spice Ultimate: My local shop just recently got this in, and I've only used it about 5 times so far, it's by far the most potent I've tried to date, too much so I'd say, because if I have anything to do, smoking even a little is out of the question. If you plan on smoking to end your day, this is the stuff for you, otherwise, get something weaker.
Spike99: We recently had a blizzard here that closed most of our town down, including my normal shop I get "spice" from. I found this stuff at a tobacco store, and decided it was better than nothing. It was OK, not great, not even really good, just OK, it did the job, not as pleasant in flavor, and the buzz was slightly different, which makes me wonder if jwh is the only acting compound(maybe CP?) I don't recommend this.