Performance impact MySQL replication vs table-synchronisation script
First of all about Variant A:


Size of bin-log will not affect to performance if You will use filter to replicate only selected tables, and even if You will replicate all - it also normally not a problem. For compare we replicate 20Gb (and more) between datacenter with real-time loading (telecom)
Keep version of Source and Target Server same - it good practice even if You choose Variant B - it avoid many other troubles


About Variant B - I personally look for tools similar pt-table-sync as for excellent but occasional tools in Your toolbox, and not for permanent solution. I can not explain drawbacks, it just personal vision

Variant C:
Tools like - SymmetricDS

Variant D:
I personally actively work now with CDC variants, when You parse bin-logs and ship them to subscriber over message queue.

I have tested under loading at least 2 working solution (really it more for now):


StreamSets
Maxwell + Talend 
Very interesting for some reasons - MariaDB MaxScale, but have not a time for make it work


I personally like this because:


have a lot of integration projects
not always source and target system same. Most resent in my case - MySQL to Redshift, DB2
It also allow realise "event-based" integration - fire Sub-Job when specific data changed 
Have more than 1 subscriber with the same producer 


Edited for add answer for question in comments:

The problem as medal have 2 (and more) sides:


Size of binary-logs - this is objective, but with good network it not a issue.
for make shipping faster You can enable compression - see more
Time what Slave need to apply all changes from Master. Even if You enable multithread slave it still slower than on Master, and by default with single thread it could be a problem with very high amount of changes on Master.


But as I wrote You can enable filter on Slave side for reduce number of monitored objects - replicate-do-table and Slave will ignore all other changes and apply only for this table (this is case of more wide filter - replicate-do-db), You can repeat this settings for several tables, or use wildcards 

Filter logic diagram

Any solution have and benefits and drawbacks, I will prefer Replication because it will apply updates "on the fly" but not only when I run the external program.