Greg, I'm having the same dilemma as you. I picked up a SiltStopper during REI's recent sale, and I went to work on activated charcoal. First I tried some cheap aquarium charcoal, which I ground down to 1.0-1.5 mm pieces in my food processor. I put 3 Micropur tabs in my 2-liter Platy dirty bag (extra, to ensure a significant chlorine taste). I tasted the water first (much chlorine taste, of course), then I ran the water through the SiltStopper and collected a sample. Still a serious chlorine taste. Then I added my Sawyer filter below the SiltStopper, let a cup flow to wet/purge the filter, then collected another sample. Still a strong chlorine taste. I then replaced the entire system and connected a Frontier Pro, with no SiltStopper. The sample I sipped tasted chlorine free!
Later, thinking the lack of good results might have related to the quality of the charcoal, I picked up a "special" and expensive aquarium charcoal concoction called Chem-Pure Elite, which also has some type of ionized beads that purportedly adsorb certain metals (maybe good if collecting water near our CO mines...). I then ran an identical set of tests as mentioned above. Same exact results!
I've sent an e-mail to Chem-Pure to see what they think about using their products in a gravity filtration system, and will hopefully learn something this week. This morning, I also sent an inquiry to Cascade Designs. I asked them which end of the SiltStopper to connect to the dirty bag, and I also asked their opinion regarding our activated charcoal trick (and if they thought of selling little mesh bags of charcoal to add to the SiltStopper).
So I'm getting fairly frustrated about this whole concept that we've been playing around with. I'm thinking that if I'm going to use AM or tablets, then I'll stick with my Frontier Pro. If I'm not worried about viruses, I'll use my Sawyer 0.1 micron filter, forgoing chemicals. Either way, I'll keep using my Coghlan's yellow filter funnel for ease of filling my Platy streamside (it also gets the bigger floaties). Hopefully, backflushing the Sawyer will remove that red dust from the Aspen area streams. I'll consider the FP disposable. Maybe Katadyn's carbon filter is the only answer to removing the chlorine taste (assuming that it really does...has anyone tried it?). But at 3+ oz, it's not too appealing to me.
I'll post again when I hear back from Cascade Designs, and also Chem-Pure. If anyone has a better experience than mine, I'd love to hear about it.