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The implications of class parameterization should be understood before committing to that approach, and those implications depend in part on which Puppet versions will be supported. I have historically been very negative about using parameterized classes with Puppet 2.x, but I am fine with parameterized classes themselves in Puppet 3, as long as hiera or maybe an ENC is used for data binding. Parameterized-style class declarations (i.e. {{ class { 'foo': param1 => 'bar' } } }) in Puppet 3 DSL still have all the problems that I took issue with in Puppet 2. This is a pernicious design issue, because although parameterized-style class declarations seem appealing and natural on the surface, they are in fact fundamentally inconsistent with Puppet's overall design. The inconsistencies play out in a variety of troublesome ways. Nevertheless, people certainly do use parameterized classes successfully, including in Puppet 2. If that is the direction chosen, however, then you will want to adopt appropriate coding practices to avoid the associated issues.
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