I don't have any quantified measurements, but my wife burns about 1GB per day, so that probably ain't 3G. We have been in the Netherlands, Austria, Switzerland, and Italy, Both hiking (7 miles around Lake Como two days ago) and urban adventures today in Rome. Because my 30 day Verizon plan costs 14 times as much per byte as her Stork plan, I'm normally tethered to her. But when she doesn't have access, I try switching off airplane mode to see if I can get a Verizon partner connection. But this rarely works, so that's a good sign that Stork has a robust set of roaming agreements. In Italy, Ubigi has one provider (Wind), while Stork claims to have 3 (Hi3G (3G), Vodafone (3G, 4G), Wind (3G))

I've noticed that it's often difficult to tell what coverage and network type you're going to get from these eSIM providers. Flexiroam shows no partners, Ubigi shows partner, but not speed. Stork publishes both (under "plans" click on "coverage/network") but has no coverage maps. But for me, the bottom line is that eSIM technology has significantly reduced my travel technology setup time and expense.