This is great stuff.
Would combining this with BitBTC shorted with BitUSD as collateral (shorting BitAssets with other BitAssets is still a future feature I presume?) help? That way you can short as much BitBTC as BTC you have on the exchange for your market maker bot and so the net effect is that you are not exposed to the price volatility of BTC (with the cost that you have only 1/4 of the total value you put up for market making for each side of the BitUSD/BTC exchange).
Since many of us are BTS bulls and are already exposed to BTS anyway, we can get close to this with the current client by simply shorting BitBTC with BTS. You can have X dollars worth of BTS converted into BitUSD, X dollars worth of BTS converted into BTC (at a price of P1 USD/BTC), and 2X dollars worth of BTS put up as collateral to short X dollars worth of BitBTC. So your 4X dollars worth of BTS gives you -X/P1 BitBTC, +X BitUSD, and +X/P1 BTC. If the price of BTC falls to P2 < P1, you take the X/P1 BTC (now worth X*P2/P1 USD), convert it to X/P1 BitBTC and cover the short to get 3X dollars worth of BTS (assuming the price of BTS has not changed). Then you reshort at the new P2 price with 2X dollars worth of BTS to short sell X/P2 BitBTC. You take the other X dollars worth of BTS and trade it for X dollars worth of BTC at this new P2 price (so for X/P2 BTC). Now you can put back the buy wall for X/P2 BTC which still maintains the value of X dollars worth of BTC. If the price of BTC increased instead you can see how a similar process would allow you to maintain X dollars worth of BTC in the buy wall after covering and reshort.
The problem with the above is that it assumes the price of BTS remains fixed relative to USD. This is why shorting with BitUSD as collateral would be better. But with this limitation it just means the price of the buy and sell walls in terms of USD would have to grow and shrink as the price of BTS goes up and down respectively. But if we are betting on eventually breaking away from BTC and all the other altcoins and growing the price of BTS relative to BTC and USD, this is a sensible strategy for our market making bots, isn't it? It allows the market making bots to maintain symmetric height (in dollar value) walls which do not depend on fluctuations in BTC price but do grow taller as the price of BTS grows relative to the dollar. Also keep in mind I am not including the effect of short interests here.