Think of base maps, CE marks (vhf radio), feet vs meters, after-sale service and warranty. Add freight, clearing charge and VAT. If it still looks a good deal, go for it.
12v or 24v isn't specifically an American thing, but it is certainly a consideration anywhere you buy DC electrical items. However, 110v versus 240v and 60 versus 50 cycle is a concern for USA sourced AC items.
Would not advise it for comms equipment (VHF), but otherwise; go ahead!
So far, have bought a radar, plotter, GPS, NAVTEX & autopilot in the US without any problems.
Warranty or after sales has never been an issue as none of the Furuno equipment I've bought has ever broken down.
The one warranty issue with the British built autopilot was honoured by the manufacturer without hassle.