Tested 138 chained transactions - seems to work, with 50 mined in each block. However, my BU node accepted all 138 trxs to its mempool, so I'm wondering if BU is propagating more than 50 chained trxs.
This is not good for 0-conf though. I can imagine an edge case where a merchant uses BCHU to verify the transactions and suffers a double spend by the 51st chained transaction.