I've thought about this some more and I feel like I cannot emphasize my conclusion enough: Parallel Realms is not worth the effort. Consider what a successful run on No Mercy will give you in 22ish nodes:
- ~500k Canopy Coins
- ~2.75 million XP (as XP Treats)
- 150 Gold Shards
- 45 Diamond Shards
- 2 Relics
- 1 random key
Meanwhile, what does a Gold Prize Fight pay out in the 20ish fights it takes me to secure a Top 10% spot?
- 345k Canopy Coins (and 5 Gold Moves that can be sold for another 25k)
- 55 Theonite
- An entire Gold Fighter
- 40 Diamond Shards (from earning a Gold Fighter)
- 3 Relics
- 2 Gold Keys
- 120 Skill Points (plus another 245 from sacrificing the Gold Fighter)
In short: overall a Gold PF has as good or better rewards than No Mercy PR, for much less "work" since the fights are so much easier. If you need XP so badly that PR's Treats look tempting, use the time to play Holodeck Hazards instead -- the fights are easier and with an XP booster you can get more total XP in one run of HH than an entire No Mercy PR.
I'm an adult with a full-time job and other hobbies besides SGM. My daily play time is limited. I will always prefer game modes that give rewards "worth" the amount of time I have to put into them, and Parallel Realms ain't it. Triple the rewards, make it a weekly, and stop wasting our time.