Isn't that the problem with whole industry? Every vendor makes it really hard to work with tools from other vendors. Furthermore initiaives like openaccess/accellera acctually seems like they are a paywall to stop others from entering the market.
Is your company big? Usually bigger EDA vendors don't care much for smaller design houses.
Btw. how are your experiences using Xyce? Do you get much speed up using its parallel processing capabilities?