I fly unflapped standard ships.
I used to fly a DG300 mainly dry. Tow in 110km/h range is not a problem.
This year I switch to a Discus 2. It has a big AoA also when on the ground and
it need about 130km/h dry to have and more speed when it is wet.

Both ship dry has the same weight and the almost the same surface. I think the main factor is the AoA. The differences are in the AoA and also in the tow hook position (baricentral for DG300 and on the nose for Discus 2) who main influence the stability on tow. When on tow we fly at relative low speed at high AoA fly in an uncommon attitude for the glider.

I always say my load and the desired speed at tow pilot befor take off.
ciao,
giovanni