I just received email from Bittrex about new policy for placing orders. My first impression is that Bittrex has problems with slowdown and scalability.
There are measures like removing orders that are older than 28 days, rising minimum allowable trade value for orders and required minimum trade quantity on a per market basis.
From a technical point of view all these limitations has a purpose to decrease execution time of most frequent SQL database queries and to maintain the required transaction rate.
With this limitations, the number or open orders will be reduced to a certain extent. This will affect filled order transactions which execution time will be faster and with more transparency.
I suppose these measures relate mostly to trading bots. I expect that bot creators will adhere their trading strategies to new rules. If this causes the Bittrex system to slow down that will probably leads to further limitations.
I hope this will be an additional reason for people to start using Bitshares DEX.