I don't think 1xxx should be added to the list of compatible units. Garmin made it, Garmin says it's not compatible. Case closed. It seems 1xxx series reportedly handle unicode better with the latest firmware, however mileage reports vary. It is however a device designed and released before unicode maps were introduced by Garmin. The EU map supplied by Garmin for 1xxx is the non-unicode version.

When the non-uncode EU was issued 4 times a year contemporaneously with the unicode version any debate about 1xxx compatibility was moot. Now that the non-U is down to 2 updates per year it has more relevance and ppl should balance the distinct possibility of search problems in U with the faint possibility of map data deficiencies and associated sub-optimal routing in non-U. Personally, for 1xxx I'd take the risk with EUU, but officially recommend for others to use 2014.40 EU and wait until August for 2015.20 rather than use 2015.10 EUU.
Everyone should just make up their own mind about the alternate risks of course, so in taking that on-board the debate is again moot.