I bit the bullet and bought the Transmitter in the end. Part of my Easter weekend has been setting it all up. I'm now the proud owner of xDrip and a nice Sony Smartwatch 3 to watch it all on (as the nightscout stuff on Apple watch doesn't work). It's all great fun and I've downloaded and am running HAPP on the same phone. It's all rather cool and geeky, but tremendously useful for keeping an eye on what is going on. Is it better than the Libre? Well, it's, different I'll give it that. And the alerts are useful overnight compared with what you have from the Libre. The libre still retains a modicum of the finger test approach where you can go to bed and kind of ignore what's going on, however if you have alarms set on xDrip, no chance.
The HAPP software is also quite interesting. it does make you think twice about your actions in a way that normal use doesn't.