I like the idea (but then I like most of your ideas!).
However, it has clear limitations. For one thing, it's going to create a lot of questions, like "what does that mean", "how do I do that", and "YFull doesn't have mine, what do I do".
For high level haplogroups, such as from 23&Me, Living DNA, and any of the FTDNA STR tests, it should be straightforward, should not be much disagreement in YFull. But for those who have tested further, there's a high likelihood of disagreement between YFull and FTDNA and others. My own goes 2 branches further than YFull, so I would have to limit this field to a higher level SNP than what I would prefer to use. And from what I've seen, YFull is having trouble keeping up with FTDNA, so there are likely to be many with higher level YFull SNP's than on FTDNA.