GreenThumb:
I have always had good results using ethyl alcohol with Tamiya paints.
So have I, mostly, but it's not so good with Tamiya gloss acrylics. I have found that ethyl alcohol tends to make the paint dry with a flatter finish. When thinned with X-20A, it dries with a much better gloss though it's better again with Tamiya lacquer thinner.
Another advantage I have found when thinning Tamiya flat acrylics with ethyl alcohol is that you can run the paint super thin (much thinner than IPA or X-20A) and get smoother finishes and the paint will still "bite".
Here in Australia, ethyl alcohol (methylated spirits) runs to about $5.00 per litre, compared to $12.00 for 250ml of X-20A, and IPA is not much cheaper (than X-20A).