These days Upper Class YQ/taxes is $2300 round trip to London ex-US so not really an economy ticket price anymore. And given that VS cash prices on the route I checked are currently as low as $3100 means your points are saving you a whopping $800 or less than a penny a point (congrats VS you Delta'ed yourself). Given that most US folks doing CCs would be better off using their flexible currencies to buy a cash ticket and offset the cash ticket price at 1.5 cents per point with Chase UR or Amex MR or even C1 at 1 cent per point. Now if cash prices are significantly higher or you need the flexibility then points may make sense (flexible cash fare seems to start around $3700).

Also there is a happy middle ground. I have had great luck in the last few years getting flights to EU from US on AF/KLM for 100-120k FB points and $500-600ish in surcharges roundtrip. Not much more points than VS and far smaller surcharges too. Even used VS points to fly them a few times. While FB saver space doesn't have quite the same availability as VS it has been pretty good in my experience. Heck I find BA RFS a decent deal if I want a direct flight to London from the US.