You’re a grown man and I’m sure making sensible decisions, just a word of warning.
You have a system now that you enjoy and is specific to your riding, on the same bike no less.
Is the damage/use on your high end bike by riding indoors really that high?
Is your wife ever going to be using that thing more than a few times?
Is riding a non-mountain bike on the trainer going to be sufficiently specific for your riding outdoors?
I see your reasoning, but also never change a running system