In the past I have kept clown loaches with this same group of fish, minus the gouramis, and have not had any noticeable problems.
I think the conventional wisdom on this arrangement is that the clown loach is nocturnal and can disrupt the "sleeping" habits of the rest of the community. Also clown loaches do get quite large, although they grow quite slowly, in my experience, and may cause havoc when they reach adult size.