Hi,
I am using PerlApp currently only company internally, I was considering similar problems and take care I am only using packages covered by the Artistic Licence or at least not GPL and similar. There is some GPL I'd love to use and my workaround is pretty sketchy and was time consuming. Yet bearing the GPL in mind I do not want to use it.
Yet I fail to understand your logic. Why do you - consider to have no problems using the proprietary tools - does your lawyers advice only cover those special proprietary licences or does this also cover more open licences as the GPL? The way I understand the GPL, this becomes even more complex. Section 3 states that I have to supply anyone I give my GPL based application to with a three year warranty to supply all codes required to build my software. I have created my very own build scripts all depending on perlapp. as they would not work with perl2exe or par, I wonder if I would even have to provide licences of perlapp for whoever would like to "compile" my programms once I started including GPL sources.
Wondering about the same problem I have recently written a letter to the Active State support. The answer was unfortunately unsatisfyingly short and did only provide the rather trivial answer "you can do and sell whatever you like" without any satisfactory reasoning into this matter.