I've had good luck with RMATV in the past. I've used the FMF Q4 (too loud at 96db) and the LeoVinceX3 (better at 94db and no repacking) but the new "trail saver quiet core insert" from Lexx is supposed to reduce sound to below 90db so I ordered one from RMATV and it arrived yesterday. I'll give it a try.
I don't think the Lexx is a very high quality pce but it's inexpensive and more importantly, it may be the quietest aftermarket silencer available for the KLR. It also has a USFS approved spark arrestor. Personally, I wouldn't put too much faith in the repacking recommendations - it isn't rocket science and every silencer that requires packing will have the exact same interval in your particular usage. I ran the FMF Q4 for three years on my 2001 KLR before repacking.