Smart trainer advice

Hi all,

I currently have a traditional turbo trainer, but am just about to move house where I will be the proud owner of a double garage! As part of the deal with Mrs Il Sole, the house is hers, the garage mine 

I intend setting up a proper pain cave and buying a smart trainer to ‘enjoy’ some better online platforms rather than just watching the odd GCN video and trying to follow on my old turbo. So, my question is this: Should I use my best bike attached to a direct drive unit, or buy an old bike off ebay which I could abuse?? My LBS recommended not using my Wilier on the trainer, but is he, (or am i) being too precious and that doing a few hours a week on it strapped up to a smart trainer isn’t going to cause any issues at all??

Of course, the outlay for all this is going to be around £1000, so I want to do it right!!

cheers!