Being PER based I have had the pleasure (?) of EK 777s about 12 times on the Kangaroo run to LHR since the Qantas/ Emirates code sharing.
Always fly Y and just to get best seats (195cm tall).
Some comments, suggestions and issues:
I am QFF points rich (600k) and usually hit 500 SCs annually so do what I can with QFF Silver.
Cannot upgrade with QFF points on PER-DXB leg due to terms of the agreement.
When booking you flight all Y seats except the emergency exits are bookable.
Can grovel for an emergency exit as long as you get in early - I usually arrive at PER 3 hours before my flight, do my standard grovel, get my booked seat changed to emergency exit and head to the Q lounge (QC member).
Tougher on the return leg DXB-PER as often not a 3 hour connection after arriving LHR-DXB - probably had a 75% success rate on emergency exits this way though had seats next to me locked out a couple of times.
I always take QF 380s for the DXB-LHR & return legs so book the row 80 window seats or cough up for an emergency exit seat if they are not available.
Upgraded with points to business once when nothing available and 4 times flew PER-MEL or SYD- DXB - LHR to go all QF metal but gave it away because the extra 10 odd hours made it such a pain.
If I have leg room I can survive Y to LHR because I have learned the knack of sleeping for most of the flight - noise suppressing headphones are a must on EK Y for that.
And a a final cough - I wish both EK and QF would load a new series of Big Bang Theory - same series for 2 years now and you can only watch so many repeats!!
Chris