It makes sense but I don't know if that is a big concern. How much data per day are you talking about?
I know I few customers that used this design to search various small locations between to 5GB to 50GB per day remotely. Not all data is transferred from the Indexers to the Search Heads. It also depends what kind of searches you perform from that central location.
One other idea but I never tried, have multi-site clusters and not use SHC because you would need site affinity on the central location. Example: Asia has a multi-site index where it keeps one copy on the original site and send another copy to the remote site (central located indexer). The local SH in Asia would be site aware and only search in Asia (unless Asia indexer is down, in that case it would search central indexer). And then same thing for Europe, one indexer in Europe, one in central location. This way you would have 2 central located indexers, one in each multi-site cluster. Then you could use the central SH with site affinity, that way it would search only the central located indexers and only the remote indexers in case the central from that cluster is down.
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