Hi Peter,
I understand a max spec i5 (RAM is less significant) will handle current Roon loads for very large libraries including 110,000 tracks and more. It may be that @evand can assist in this regard (he’s got a big 'un 
).
But current Roon loads are not future Roon loads. If you have the half dozen or so zones of a normal house (as distinct from the Scottish castles I understand @danny likes to roam, transferring zones as he goes) you could do some parametric EQ in each Zone simultaneously (for example) and still not overly tax a full spec i5.
When you start upsampling and convolving Room EQ, however, things start to change. If you were upsampling to say DSD 128 and convolving to one Zone only and using some EQ in others, then I think you might find an i7 would make a difference and as soon as you start upsampling and convolving to multiple Zones (especially multichannel convolving) then I think you would definitely need the extra grunt of an i7. In a little while we will all be able to check out how these sorts of workloads affect our hardware.