Should I get TooSIM for Europe or is train Wi-Fi more reliable when crossing borders?

​@TeresaW 

Not all European trains have Wi-Fi. For example, in Switzerland, only a few international trains have it. It depends on the country and if you take long-distance or local trains.

The reception with eSIMs can also be very poor. Sometimes you have only 2G or 3G, or no reception at all (e.g. in tunnels). And Wi-Fi use the same networks, if you don’t have a connection with your eSIM, Wi-Fi will not work better.

It’s been a while since I needed to buy an eSIM, but a quick check suggests that’s about the right price.

Do check that your SIM covers you for any non-EU countries you may be going through (eg Switzerland, UK).

I would 100% be wanting data on my phone, rather than rely on wifi. Not just for my pass, but for checking timetables during disruption, and for Google Maps & Translate, if nothing else. Some trains have decent wifi; others have none, or are unusable (Eurostar, for example).

Yes, they work fine at speed. IIRC, the GSM specifications were designed with high-speed rail in mind.

I managed to do switzerland without mobile data. As i did not feel like paying extra just for 4 days (but i had to go back to my hostel once because i forgot to activate my travel day.) But many trains dont have wifi, so do not rely on that. 

But recently i changed provider so that switzerland is also included. (i am from Germany ) If you need for example switzerland make sure your esim includes it.

Network switching at the border usually works well. Although i once had issues with the slowakian network where it took me 30mins to get a connection. (but once it started wirking the connection was fine, no idea what was going on there )