Use the EA5 until it dies or C4 does some updates that are not supported and you need those features. You should be able to get several more years out of the EA5, if not longer, and then if it becomes obsolete there is always a market in EBay to salvage a few dollars.
Your summary of your house isnt all that different than mine and I have some complex programming involved and I have an EA5 and an EA1 and it works fine. The Core has a little speed bump I think and a few features geared towards higher resolution audio, but as far as running a house like yours, it’s fine. If you needed more performance you’d look at a CA10 (which is going to be overkill I think)
