This one is mostly thanks to Paul Ockenden's PC Pro column. The magazine has survived the changing IT landscape well and a subscription is good value for money, IMO.
As mentioned a couple of months back, one annoyance about my new smart watch is Samsung Pay, which Monzo do not support. Given their client base, and given also that such "legacy" banks as Nationwide and the Co-Op (neither famed for their IT) have managed to support it, a conspiracy theorist would wonder if Monzo are deliberately taking a stand against fragmentation of payment services. But it's probably a good old-fashioned lack of developers.
Either way, an "aggregator card" like Curve - which supports Samsung Pay et al - is a neat way round this. It simply "forwards" transactions to the underlying card, which can be any MasterCard or Visa (switch between them in the Curve app). As well as fixing lack of support for Samsung Pay on Monzo, this could also be useful to anyone with a "work" credit/purchasing card, since none of the banks seem in any hurry to add even basic Google Pay support to these.
Naturally, having another layer involved in the transaction should make you a bit nervous in cases of large purchases or anything where a refund might need to be requested - especially since your finance team at work might not be too keen on finding out you're using a third party card "in front" of your company issue one.
However, the solution to this seems simple - use Curve for the small(er) stuff when out and about, e.g. travel and subsistence. It's things like paying for the tube which is so much easier with phone/watch than digging the right card out of your pocket - and for the big ticket items, you're probably sitting at your desk with plenty of time to fish out the actual card and use it directly.
Downsides? Well, the items appearing on the underlying card statement are all prefixed with "CRV*" - you do still get the original merchant details after that, but it makes it a bit harder to follow and makes a slight hash of logos and stats on Monzo.
Also, activating the Curve card on Google Pay and Samsung Pay requires confirmation text messages, which failed to arrive for me until I phoned Curve and they fixed something at their end.
All that sorted though, I should finally be able to use Google Pay when travelling for work, and use my watch to pay via Monzo in places which don't support American Express.