Well... a few days with 50 A4+ now and they really do suck.
I've got all 50 in Awesome Miner so I know when they stop mining and the stats aren't good.
If I mine on a pool that isn't 100% stable/efficient they can't handle it and where I assume the AntMiner D3s/S9s I have just deals with it and pick up where it left off the A4+ stops mining and restarts the mining process, losing you 5-10minutes of shares. NiceHash is a complete no-go too, they're can't handle it for some reason (vardiff?)
I'm using litecoinpool.org and this does appear to have helped stability. will update again in a few days.
The difficulty the pool gives you just adjusts the amount of work you do before returning results. Giving you a low difficulty when you have a high hash rate means that you're banging the server more frequently, asking for more work and returning results, which will greatly increase server loads, which can kill your pool.
those are the work around I can think of to help with this
Option 1try to split your 50 miners over the 4 servers of Litecoinpool
stratum+tcp://litecoinpool.org:3333 (Europe)
stratum+tcp://us.litecoinpool.org:3333 (US East Coast)
stratum+tcp://us2.litecoinpool.org:3333 (US West Coast)
stratum+tcp://ltcpool5brio2gaj.onion:3333 (Tor hidden service)
this might help you to decrease your hits to one server and hence lower the diff you will be given
Option 2split the miners over multiple litecoinpool accounts not workers
Option 3spit the miners over multiple real IP's
I hope any of those helps