Hi!

clients have specifically expressed a concern about the ability to maintain our/their Web apps written in Perl should my business go bust

That is -of course- a legitimate concern. However it is not perl-specific. If your system would work with PHP, the concern would be the same.

Possibilities to address this concern would be

• show that perl is a mainstream-language, nothing exotic (e.g use the Tiobe Index)
• show that there are thousands of capable perl-programmers around ... not only PHP-coders
• show that your system/code is well-documented, so anyone can take over
• prove that your system is as stable as others (after all you are in business for 10 years)

So the programming-language you use should not be the biggest issue. However (as CountZero wrote) you will still face the competition of the open-source CMS systems...

HTH, Rata