No, would make zero sense to overhaul my aircraft come TBO. Probably not make any sense on any -5 powered 690A/B either. On -10's, it probably won't make sense financially either, but the gap is small enough it is prob worth it for utility.
The choice many face at the end of TBO is continue to run them, or find a lower time engine somewhere and buy that.
That said, here's a crop duster guy on another forum talking about PT6's over TBO:
Yes, we completely ignore TBO. Our planes currently range from 10,000-14,000 SMOH. That said, we do comply with HSI intervals and usually do them as much as twice as often as recommended by Pratt. If you have someone who will treat you right on hots, they can be a good way to save money. In addition to finding discrepancies while there is still time to repair instead of replace, frequent hot sections can be a vital tool in determining if current operating practices are allowing for the most economical outcome.
Our in house limits are currently 1000 hours on starter/generators, 5000 on CT blades, 1500 on hot sections, 5000 on FCUs, High pressure fuel pumps, and power sections. Most every thing else is done "on condition". As far as cycle limits, we strictly observe them on all rotating components.
The results have been outstanding. Dispatch reliability is nearly perfect and operating expense is only a fraction of what Pratt quotes.