Do not confuse Snapshot Isolation with Read Committed Snapshot Isolation. Snapshot Isolation is enabled at the database level, however it is only utilized when a SQL batch explicitly asks for it, i.e. it will have no effect on existing clients unless code changes are made to explicitly ask for it. For your in-house batch you could utilize it, but other batches submitted by pre-existing code would not be affected. Enabling it does however fire up the version store in tempdb regardless of whether anyone is explicitly asking to run code within the snapshot isolation mode, so those concerns still apply.