Get them both in your house with your system and then decide.
If this can be arranged, then unquestionably it’s the best evaluation method. With regard to WBF , he’s more likely to get replies from those familiar with the components of interest. They are pretty good at staying on point in my experience on that site.
Certainly there will be respect for his decision as an adult to spend his money as he sees fit. Rather than the tired and stale references to the cost of a given audio product and questioning one’s judgment for expenditure.