Some useful feed back for Interphone: my f5xt had two hairline cracks on the white housing where the wire attaches. After a few photos and emails to Interphone in Italy I was told that it would be covered under the 24 month warranty. So I sent the faulty unit back to Sportsbikeshop.co.uk where I purchased it from, again after a few emails and a phone call to thier customer service. A new f5xt was in my possession within 10 days. Excellent service from both companies. Only cost to me was £6 for postage. Just keep your invoices for the original purchase.
I've had battery problems and sound issues on both of my F5MC's, and finally after a 4 week wait, Interphone have replaced the whole lot, and sent a new retail pack to me.