Yes downgrade comp should apply as well regardless.

I would say that is a pretty significant downgrade from D1 equip to connection in domestic F and then Y with resultant delay of 7hrs.
Looking at flight history for DL 261 KEF-MSP, I'm guessing this occurred on Sat 6/2. Flight departed KEF over 6hrs late. Problems started several flights earlier with a 5hr late JFK-ATL-JFK route on Friday of which DL never recovered.

Lets face it, OP is not going to get $1000, unless the flight difference was actually that much from D1 to F/Y for MSP-HNL. However, definitely fare difference for the downgrade, plus the downgrade comp (what is that, $200+ for D1 to Y?) and something additional in form of goodwill for the significant delay and downgrade... but that part is likely to be in the form of miles.