Hi Prue,
I did it last year.. and finished
Yes, the climbs are massive, more technical than UTMB. Like utmb on steroids is how i described it.
HILLs, hills hills and more hills is prob your best training plan for TDS. Ascents are massive, but the descents go on forever, so be careful, dont burn out by Bourg (as i nearly did). Take care of the quads, they can be destroyed on the downs.
Was very hot last year, dehydration was the problem, it was about 26-28 deg through the day, maybe 20 at night which was lovely. and warm breeze. But generally (i done utmb 3 times) night sections require a long sleeve top , maybe a windproof also.
I carry poles, some do, some dont. I use Mountain King Trail Blaze.
Watch out for the col de Tricolet? cant remember exact name, but its after Contamines, towards the end. doesnt look much on the profile, but has to be the steepest climb on the whole course, wiped a few out.
If you need more info, ask away!
Good luck, its a fantastic race. Its much wilder than UTMB, and very rerwarding to finish.
Mark