On the proposed "Sharded Transaction Limit"
The sharded fork is a good idea for improving a blockchain system's N traction limits, where N is the amount of transactions but could benefit from having a sharded transaction size limit for each sharded fork. By setting a maximum transaction amount per sharded for SiNamount <= amountmax i where i is each sharded fork.
This allows for scaling the security of transactions in terms of nodes verifying each transaction for the amount of coins transacted per block.
An example:
Shard 1 can verify amounts up to 100 coins per block and has x proving nodes
Shard 2 can verify amounts up to 200 coins per block and has 2x proving nodes
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Shard N can verify amounts up to N*100 coints per block and has Nx proving nodes