I have the same question...
My suggestion: compare these to the gens, and see with which of the flaws you can live with...
Also things to consider:
1. Mineral Crystal vs. Sapphire (especially the 212)
2. The 212 with the "right" (internal second markers) is only manual, while the auto has a wrong dial
3. PT has a thread WAY in the past claiming that a new 253 with improved face is imminent (I think it's on TRC, not here). There isn't one yet, but maybe someday...
Flyback means that you can restart the chrono without stopping it - there was a long thread about why this is needed... don't remember where though... (and I don't think ANY replica has that feature anyway)
Hope this helps. Will be happy to know what you chose and why... might help me with my own deliberations...