Negative impacts concerning Circular References

Practically speaking we almost never bother to fix them nor do we see any apparent benefit to taking to time to do so.  I guess the answer might depend on what you're creating.  If this is something that is going to exist for a long time or be used over and over again in other designs, I'd be more prone to clean it up.  If this is a one-off design, then I probably wouldn't bother.

It depends on what the data is used for. You will have to determine based on your situation whether or not you permit this. Most large Creo organizations will not allow a model with circular references to be checked in to the PDM vault. This forces someone to fix it before the data is vaulted.

They have the potential to kill productivity in the event that a design must be changed. I have had to clean up projects where the .crc errors were preventing the organization from making wanted changes to a design. In almost all cases I end up rebuilding some or all of the models. Obviously this is costly. They can also cause very unexpected results when changes are made and could go unnoticed.

I would take the position that if Creo Parametric is your MCAD tool then you should not accept models with circular references created by your users. If you are provided external data that have the issue I would come up with a plan to deal with that.

I agree with all the other comments. I sometimes fix them and sometimes leave them. I also agree that if you work on large assy's and you have more than one or 2 CRC's, you're paying a price in time for those issues (along with other regeneration errors).

BUT, if you are copying (save-as) assemblies with plans to reuse some of the data, CRC errors can cause significant issues. These include unexpected retrieval into memory of assemblies that seemingly have no reference to each other, unexpected save-as/rename issues that require inclusion of sub-assy's that are part of the CRC issue, and our biggest issue was a PDMLink error that was not letting us check in a large assy that had a combination of circular references and drawing references (all was fixed by PTC) that was extremely frustrating for some time until a fix was implemented.

Truly getting to the root of them can be mind-numbing, and will likely frustrate your end users, especially if they don't have the rights to change everything that may be related.  Maybe practice on a few different projects and make sure you can consistently eliminate all of the circular references in a timely manner before putting into place an official policy.