Has a lot of effort been put into tsume-go? Maybe I'm a bit out of touch
nowadays, but I always felt most programmers put relatively little effort
into tsume-go. But I do understand why, it's hard to incorporate the
single-goal program usefully into a more complex whole and make it worth
the investment. I've found that PN-search is extremely promising to
overcome that problem, but haven't heard yet that anyone is actually using
PN-search in a playing program.
I think Go Tools is 5 Dan or stronger at Tsume-go, but it doesn't play go, just