Phil,
I had a problem when applying lettering to an etch I did some time ago. I was using AutoCAD LT and it was not good at producing a decent font. So I used CorelDraw to produce the text and imported it into CAD using DXF, and all looked well. The etch was twelve small etches of the same part all with the same amount of text repeated on them - Part name, part number, description and copyright symbol. I sent it off to PPD and got an email back the next day saying that they were having problems dealing with my .DWG file for the etch in that it was very large. I had a look at my source files and eventually tracked the problem down to the imported text from CorelDraw which had thousands of minute vectors. I couldn't find a way of reducing the vectors from CorelDraw, but found a way to produce the text in Acad LT which had a much smaller count of vectors.. So if you do find a way of producing your text, watch out for the vector count in the characters.
Jim.