I just went DPS in J last week. Most days CX would use regional 773Z aircraft with regional J product. IMHO, the regional business class seat sucks and the DPS flight is long enough (4h30mins my flight time) to make you realise how uncomfortable it really is.

On the day of my return, KA flight got cancelled and CX sub a longhaul 77H to operate and my flight has been oversold by 40+ pax (check in agent told me at DPS). As a DM and J pax, they moved me to 1A in F! So I was lucky...

Catering on both flights were very average, per usual.

I'd say if you're using your own money for J then don't bother! You could save all that for a nice suite on the island. However, if you're using points then I think it's worth it given only 15k points difference. Afterall, a 4 hours + flight in an uncomfy business seat is still better than in an even more uncomfty economy seat