Hi Daniel,
First, I wasn't suggesting profile inheritance from Sonar way, but that the concept in general would be helpful to you. Re-reading Victor's initial email, I guess when he said
forces my team to duplicate the entire quality profile and make changes by ourselves
the profile being duplicated was Sonar way? I thought he was working from a copy of the company's profile, and my suggestion was to split the company profile into "core" and "nice to have". Leaving that aside, that initial duplication of Sonar way, rather than editing that profile directly, seems like the best way to keep life simple. You start from a core set of rules, and can then start adding and pruning. The reasons to keep Sonar way separate from your edited profile should become apparent below...
We've actually worked on how to know new rules are available in 6.0 (RC available "soon"). If you upgrade quickly, that should help some, but looking back at Victor's initial email, it seems that you're still on 4.4 (really?) so, uhm... yeah.
But there are a couple of already-available features to help with this.
First, as you alluded, do a Restore Built-in Profiles after each plugin upgrade and compare your profile to Sonar way. Assuming that your base profile isn't far off Sonar way, this won't be too bad, but yes, it's tedious.
An even better way is to use the Rules search. There's an Available Since date-based search facet, which you can use to find rules that were added in a plugin upgrade (so yes, you'll need to know approximately when the plugin was upgraded). This will show you all rules new in that version. You can combine this with the Quality Profile facet to find only the new rules that are active in Sonar way by default (assuming you've done the Restore Built-in Profiles step). Note that I don't remember which version rule search was refactored in, so these facets may or may not be available in 4.4.
HTH,
Ann