Ah, interesting input, Anke.
Shetlands have the widest pelvis of any sheep, I think, so will lamb a Texel cross lamb more readily than a Swaledale or Blackie!

If the Gotlands have a narrow pelvis, then caution is definitely advised. Note that you can't tell pelvis width from the size of the animal. (Same applies in cattle - Jerseys have the widest pelvis, and are one of the smallest cows.)
With our Texels, it's more the hips / backends that stick. Very close, fine ("thin") "skin" (fleece) really helps - much less friction.

That's one of the things that is good about the Charollais - very fine skin, verging on bald

- makes them very slippery and easy-lambed. But also makes them 'soft' and not hardy to wet cold weather, so we (a) select a tup with a woolly head (generally means more fleece on the lambs) and (b) keep the little plastic macs at the ready, and coat any young Charollais lambs if it's going to be wet - or even bring them indoors through any really bad weather.
Charollais tups vary, same as any other breed. Our boys are carefully selected to suit our climate and flock.
We specifically select our tups - of all breeds - with narrower shoulders - no-one pays you a bonus for wide shoulders. Big gigots, though, are worth £££.