Much of this potential confusion would disappear if the OPers would clearly identify the model (e.g., -12 versus -iS, Dynon versus Garmin, etc.) of RV-12 they are referring to. Either put this information in the OP or the OPer's signature.
What is the downside?
Because the two models have so much in common, I think the downside to having two separate forums is that most RV-12 and RV-12iS owners and builders will end up reviewing both forums anyway.
For example, if there's a problem with the wings, empenage, fuselage, canopy, etc. on an RV-12 and you're building an RV-12iS, wouldn't you be interested in knowing about it? Likewise, if you're building a -12iS and have a problem with a part that is common to both models, wouldn't you like to know how an RV-12 builder resolved the issue?
I think what most guys will probably do is post the same question in both forums, which means there will be a lot of duplicate posts to wade through.
Speaking as someone who moderates another forum, multiple posts on the same subject by the same person in different forums are a royal pain in the you-know-what for both the original poster and those who reply. It's definitely something to avoid if possible. Much like sentences as long as my first one.So what is wrong with that? I did an 12iS but constantly checked all other forums, like RV-12 and RV-14, for ideas and suggestions.