Well, the customizations are to the C++ code and it doesn't feel particularly difficult to adjust, but then we have years of senior-level C++ coding behind us.
One of the first changes we made to sphinx was just to increase the minimum word length so that queries could be extremely long (as error messages sometimes are quite long). This was changing a define and tweaking some other areas internally.
We also made some changes recommended by others in the sphinx forums and have been adjusting the weighting algorithms for our own needs.
No plan, really. The changes would need to be #ifdef'd or otherwise conditioned-out because almost no one would want them. We optimized it specifically for our own error message searching and that's not really very useful for practical use.
For adjusting the maximum query length, you can find tips on that in the sphinx forums.
