The LSL is the Low-Dome (flood effect for the Luxeon) and the LSH is the High-Dome variant (further throw).
I highly recommend putting in the extra money for a Premium, i.e. LSL-P or LSH-P. I like my LSL-P a little better than my LSH-P, even though the LSH-P is more whiter, brighter. I just like a wider flood pattern for the use that I put the LSL-P to.
If you have a KL1/E1e or KL1/E2e, the LSH-P will likely be more brighter than either of the two. At least that's been my experience when comparing them to my KL1/E2e. Colorwise, my LSL-P and LSH-P are still brighter/whiter than my KL1/E2e.
It really depends on what you're going to use the Arc LS for to determine your satisfaction... but I can understand the need to be "coaxed" into believing this is the right thing to do. Believe me, I do the same thing all the time.
I use my LSH-P for general work around work/home when I need a light... very handy, very useful. Plus, its size and craftsmanship makes for a bit of a wow factor, especially since I can fit it in the coin pocket of my jeans. Not bad for a little power dynamo.
For me, it's been a great investment. I didn't buy the nylon holster though... it seems small enough to just throw in the pocket. But you might want it to be more readily available.
-Jim