Haha that's entirely a "you" question!
Here is my *subjective* rationale: there is a certain threshold I don't want to cross, otherwise I feel I might as well just make the leap to go gen. For me, that threshold is a maximum of 5% of a watch's current market value.
The 15706 is actually my favorite watch! I bought a new XF v3 and later a lightly modded "v2". So total all-in including fees/etc was $950. You can get a gen 15706 for as low as $17,000. So I already spent 5.58% of the market value of a gen already. No matter how close to gen I make the watch, it is still a rep at the end of the day, and for me, under my current perspective, the greatest allure of a rep is the value proposition of its low entry. Especially the XF FC 15706; I feel this is a watch that can be enjoyed OTB and further investments offer greatly diminished returns.
However, because the Schumacher, for example, commands such a high market price currently, that would be a watch I would probably have much more flexibility with in terms of mods / etc. In contrast, I have also been looking into the FC GP. The stock JF v3 FC GP is not that great OTB. But any decently modded one is around 3k USD. A Gen goes a low as $22k so I'm having a hard time justifying getting the modded rep since it would be 13.63% of the Gen's price already.
On the other side of the coin, I understand that instead of just looking at the numbers, there is a passion and a journey aspect involved in modifying / going franken--a value which cannot be quantified in mere numbers.
Again, this is all just my current opinion. If you asked me just a few weeks ago, I would have been very adamant in enjoying a rep purely in its stock form.
