Futaba R603FF v R603FS 2.4ghz???

[Spoolio]

I have a Futaba 3GR radio and due to a cock-up at the North Pole sorting office Santa left an R603FS receiver under the tree rather than the spare FF I put on my list. Not being one to look ungrateful I plugged it in not expecting much but was pleasantly surprised when it managed to bind to the tranny OK. Question is, am I likely to damage it long-term or is it a case of if it works now it should carry on working?

The only external difference appears to be a differently styled label on the top of the unit (blue rather than orange highlighting etc).