We tup 220-250 commercial ewes each year, using Texel, Dutch Texel and Beltex tups. All lamb outdoors.
The ewes are predominantly Texel X, with some Charollais, Dutch Texel and other breeds in the mix. We have a few NC Mules, and breed up replacement ewes from them using the tup breeds listed.
We do get the occasional lambing that needs assistance, but so we would with any breed. On the whole, it will be the ewes that have the most Texel in their makeup that need help, and the Mules need help lambing less (though may need more help with the lambs, due to more triplets.)
It's a fact that a Charollais tup gives easier lambing in our flock, but we have to watch for newborn lambs in cold weather in case they are too bare. We don't use a Charollais every year.
A good (not too wide) Dutch Texel is the best option with our flock, but it is becoming increasingly hard to find one that isn't too wide and stocky. We've tried a Beltex x Texel tup this year instead.
You've done the right thing not feeding concentrates until the last few weeks. Fodder beet is very nutritious, though, so if they've had loads of that there may be some well-developed lambs...