I have a Pentax digital spot meter in perfect working order. Was calibrated by Ritter a few years back.
Was looking for a sekonic 758, 858? spot meter.
I miss having an incident meter and don't feel like having multiples.
I think your best bet is to sell the Pentax outright then buy the Sekonic. Why I think so? Because I think the people who value the Pentax wouldn't own a Sekonic.
Get, or keep, the Sekonic, which I presume from your post is the L758D/DR. In skilled, experienced hands the Pentax has nothing against the Sekonic. I hasten to emphasise though it is the skill and experience.of the user that governs how useful or otherwise a meter is.