Hi takai, I dont think anyone sells the Lelit machines in Adelaide but I havent had my finger on the coffee-pulse much lately so could be wrong.
The Lelits are good machines and very similar to the Silvia. In terms of their operation it is effectively the same for both machines. For the extra $100-200 I would go the Silvia, slightly better build quality and commercial size group (easier for spare parts and accessories). Great re-sale value too.
$680 for the Sunbeam combo is tempting but I would highly recommend an extended warranty. Youre then looking at several weeks each time there is a repair required.
The 6910 would probably be easier for your wife to operate - not as many steps required compared to the single boiler machines. In my hands the quality of coffee with the 6910 or Lelit is similar even though they are completely different beasts.
If it were me Id buy the Silvia and just make my wife the coffee each time she wanted one (which is actually what I do).