Thanks for the generous response.
If I was trading spreads right now I'd definitely consider other markets.
Although fixed income is where I have the most experience in the past I have dabbled in spread trading most futures although not equities; though I know the maths well enough.
In fact I'd stay away from spread trading quite a lot of fixed income for another year or so. Why? Well once we're out of ZIRP the spreads will be much better behaved in rates (so as a simple example the duration weighted 2y10y spread wouldn't end up being an outright 10y bet due to the relatively low vol in the 2y).
However I'm not currently thinking about spread trading for a number of reasons.
My current directional futures system is consuming all my risk capital. To trade something else I'd need to reduce the diversification I have in that system. On paper it would make sense to do that if the sharpe of the new system was significantly higher.
On paper it would make sense to trade something with more negative gamma, to balance out the positive trend following. A decent short biased options system would have a good sharpe ratio (north of 2.0), but the engineering involved in getting clean data is relatively involved.
Trading fully systematically as I do, spreads are also slightly more difficult from an engineering perspective. So for example getting a tradeable sychronised price might be tricky. Just looking at closing prices is fine for a slowish directional system, but the spread of closing prices may not be accurate. Obviously some intra market stuff has a tradeable spread price, but these might not be liquid. These problems then map on to the fully automated execution algo, which again needs to be far more involved than for directional trading.
These problems are all soluble (and with about one third the work of building an options system) but right now its not a project I want to commit time to.
Your honest discourse I for one encourage. I traded CBOT, CME, Eurex, and Liffe interest rate spreads from 1992 until about 2004 ( pit and screen ). I also from time-to-time traded cash basis. Your comments are certainly spot on for the rates.
Having said that, I would encourage you to dip your toes in the water with some other markets - especially energy and grains in terms of intra market spread trading. If you can trade interest rates you can trade those other markets as well. There really is a great deal of opportunity there, especially if you stay away from the prompt months.
Most of the inter market spreading I see amongst clients, outside of interest rates, is with the stock indices and actually baskets or individual equity names.
I would agree that for the most part, an inter market spread will typically show a great deal of momentum and acceleration in terms of convergence and divergence. Typically much more so than intra market spreads. And as you say, "horses for courses" - some clients like it and many don't have the appetite for it.