I booked a economy reward ticket yesterday, and am now considering switching it up to business.

Current itinerary:
YYZ-PHL-LHR (stop1)
LHR-ZRH (stop2)
ZRH-SIN
SIN-AMS-EWR-YYZ

Departing Jan 17, returning Feb 2 or 3.

The route coming back is long-winded, but unfortunately that's what's available without the fuel surcharge.

Would it be worth it to upgrade the trip to business? The catch is, it'll only be for around 44% of the flight time. $150 extra cost and 50K extra points.

YYZ-IAD
IAD-LHR (econ, 7h15m)
LHR-ZRH
ZRH-BOM
BOM-SIN (econ, 5h25m)
SIN-LHR (econ, 14h5m)-IAD-YYZ

If not, what's your threshold?

I am still trying to find a better routing, but so far no luck.

Apologies for the inexperienced questions. First time doing this.

Thanks!