I've used their oil painting cleaner on some inexpensive oils in the past and it does a good job of cleaning. However; On a painting of any significient value I would still bring it to a fine arts conservator.
This is roughly comparible to doing you own work on a double of modest value which I and many others here do on a regular basis. However; I for one wouldn't tackle something other than a trivial problem with a fine English double.
I'll take some before and after pictures the next time I clean something.
Jim
