I am so happy to hear that your son is doing great with his OPUS2. I also use the XS battery pack size and love how small it is. Keep us posted on upgrading. Fingers crossed the timing of Sonnet 2 works out!
Yes, we are definitely looking to upgrade our son's Opus 2 and had bet on the possibility of having sonnet 2 avalaible by 2019 as apparently could happen. During last summer we decided to repair one of his Opus 2s out of our pocket in order not to waste the every 7 yrs chance to upgrade freely that spanish social security provides. Hope sonnet 2 could be a reality soon as Opus 2 is supposed not to be repaired anymore therefore, if anyone of my son's opus2 had any problem we would be forced to upgrade to Sonnet 1.