I use a 34 / 29 which made the D's Staircase a bit of an anti climax, as I said on the Elenydd thread - though I should have kept that to myself, as I later belatedly realised how demoralising that might have sounded to the folks who had to walk it - I still say/type what I think, and have little ability to judge how others take things, so apologies if I upset anyone!!
I shall be looking forward to these challenging climbs.
My climbing technique includes slow seated climbing, for best traction, pulling on the up stroke as well as pushing on the down, plus regular out of saddle for a change of muscle, but again at an often ridiculously slow speed, and again watching heart rate.
We are all different, but I find that for me, heart rate is the deciding factor - I can easily ride faster, but then sooner or later I go into the red and overheat, hence my developed technique of riding slower to keep a lower heart rate...