EJE - sounds like it's a numbers game for you, like you say. 2/5 sounds great, must have been a major blow your last few cycles that you haven't had any normal embryos. I don't know much about balanced translocations (my PGD was for failed IVF/recurrent miscarriage) - do you know if they test your embryos for all the chromosomes or just specifically for the BT? If they don't test all the chromosomes, a small chromosomal problem (random) might have been the reason these 2 embryos didn't take? Your egg numbers sound amazing, which is great, especially as you only need a small dose of FSH - but OHSS each time would be horrible. I was on 600 units to get about 8-10 eggs, my ovaries aren't very good, even though I'm only 33 - my FSH was high.
I can see why you've kept going and I would encourage you to keep doing so (if you can!) from what you've said - sounds like it's a lottery and if you keep going, you will most likely get there eventually. How are you coping with all the cycles?