As mentioned, FR =fire rated.
Some, probably quite rightly, don't like them for reasons stated.
On the other hand, i have fitted hundreds of 'em and yes, they do run quite hot with standard 50W mains GU10's, changing to low energy lamps would over come that, if you felt it was an issue for you. If cash isn't an issue, you could consider some nice remote control LED colour changing sets, they look great.
In your case, i would still advise them as due to their enclosed design, they can help prevent heat loss into the loft, they maintain the fire retarding quality of the ceiling and they can prevent dust coming down through the fitting.
I'm not suggesting you must fit them, but given the relatively small price increase, i would still advise fitting them. Also, if you do not know for certain whether they are required or not, then simply err on the side of safety. Everyone's happy then