I bought access to one of their lite nodes a little while ago. Used it fairly regularly, but traffic there seems to have fallen off a bit. I suppose it also matters which tribes you're following.
I notice a lot of issues lately with ability to top up the sphinx wallet via lightning invoice. Been getting various error messages despite trying at odd times the last few weeks. Think whatever 'lite node' access I purchased from Sphinx stopped working .
I finally got it working through my Umbrella node. There doesn’t seem to be a lot of activity. I kind of get the concept (pay sats to send messages), but so far everybody seems content of Telegram.