Although I'm in the camp that welcomes research into computer go and is pleased by progress, I'm also in the camp that believes current programs are probably significantly overranked, for various reasons - people not being serious when playing them, not analysing the program's weaknesses, etc. I also believe that computers that do score well do so often because they have strengths that work against amateurs but that would not work against professionals. In particular, they seem to have a pretty powerful endgame. I reckon even dan players among amateurs lose 10-20 points per game in this area. Most pros, however, claim to play a pretty good endgame, and mistakes are usually only of the order of a point or so.
There is also the point that the weaknesses of programs have not been properly studied yet. I know, for example, that when I have played programs, I have often tried to engineer unusual positions such as semeais and sekis which are both difficult enough perhaps not to have been taken account of in the programming and which require extreme precision, something Monte Carlo may be bad at. My experience is that programs play utterly stupid moves in these cases. I am sure a pro who dedicates himself to studying these weaknesses would do even better.
The argument about computer weaknesses is often countered by the claim that they exist but are sorted out over time. This has certainly been true in chess. The horizon effect, lack of random play and taking the program out of the book were all strategies that even weak amateurs could use for a long time but are now irrelevant. Among chess pros, the strategy of playing close games with as few tactics as possible has also been demolished.
But I do wonder if this really will apply to go (except in the very long term). The nature of go is such that it involves several battles over an entire game (and can be made to have even more). One mistake in chess is usually fatal against a computer. In go you get to fight again. But on the computer side, the very programming strategies that have been devised to deal with the huge branching factor involve a large measure of randomness and therefore (I presume) mistakes. You could argue that, because it is go, mistakes don't have to be fatal for the computer no more than they are more the human, but I suspect there might be a major difference. The computer would be unaware that a mistake has been made, but a pro would be aware. The computer finds it hard to change its behaviour, the human is designed to create coping strategies in new environments. Intuitively, I also feel a pro would be able to find enough precision to punish a mistake whereas a computer of the current type would not.
I also have reservations about pro reactions to computer go so far. I think there has been a large measure of politeness, or maybe noblesse oblige. One exception may have been when a program called Erica won the World Computer Olympiad recently and so got to play young Fujisawa Rina on six stones. She made a monkey out of it, relying on a large semeai strategy incidentally. She made it plain beforehand that she wasn't going to go easy, as previous pros have apparently done, although she hadn't made any special study of computer go. This game doesn't seem to have appeared elsewhere so I give it here as another GoGoD Christmas present (thank TMark as he transcribed it).
As regards pros going easy on computers, I do know this happens. I can't speak for every case, obviously, but many years ago, when I went to Japan to help market the British-made computer Shogimaster (program written by David Levy's team that had won world chess programming titles), we had the benefit of this sort of behaviour.
We had already encountered, in various visits to major Japanese companies that we hoped would take on production, and to universities doing shogi research, a resentment that a non-Japanese team had made such a product with a previously unheard of level of play. But one evening in the Shogi Renmei (where George Hodges and I were billeted for the week in the pros' overnight quarters) we were invited to the poshest playing room and a senior pro deigned to play our program, giving a four piece handicap (which meant he was treating us as potential dan level). Not only that, he let us win. Very soon after someone at the Renmei arranged for a reporter from a major Japanese newspaper to interview us about this scoop of beating a pro at our first attempt (and we even got paid for the interview!).
I regard that as pure altruism, and I have seen that sort of behaviour countless times. I therefore factor it in when I see pro-program games in go.
Although I'm a computer go fan, I will be rooting for John Tromp, by the way.