Tup behaviour and the consequences can be quite breed specific. As a rule of thumb, horned sheep and primitive types are likely to be more feisty than larger, polled, commercial types.
And an entire tup with full headgear, even of a small breed, can easily kill a polled tup that's much bigger than him (even if he wasn't really intending to), so that's another factor if you have more than one breed.
After that, the two biggest factors against keeping them entire, to me, are (a) risk of escapes
(*) and impregnating neighbours' ewes and ewe lambs - most will be pretty upset to have a Soay cross in amongst their girls!, and (b) lack of flexibility in managing fields and barns if the entires end up staying on into winter and beyond. (Which can happen even with faster-growing sheep, let alone Soays and crossbreeds thereof.)
If you ring as nearly newborns, there is no appreciable setback. Farmers who burdizzo later on say it will give them a two week check in growth. Entires who have't gone by the time hormones start (as early as August with some breeds, usually later with purebred primitives) will probably stop growing until spring, so unless they are gone by the end of the summer you will have them for winter, or will have to send them off smaller.
With commercial types, feeding to get weights and top condition early to hit the best prices, unringed can be preferable as the wethers can tend to fat more than their entire brothers. But unless the majority can be away at the optimum weight and condition before the hormones kick in, you end up losing on the later ones as they have to be sent off a bit light and sharp before they start to be a nuisance and / or stop growing, or have to keep them through winter so they end up costing more and literally eating the profits you made on their older brothers.
So a good tactic with that sort of sheep can be to only ring runts and triplets for the first week or two, then ring all the twins as well for the remainder of lambing, and by second cycle and beyond, ring everything. That way, the entires *should* all be away early, usually before weaning, and you do get the benefit of the stronger, leaner, faster growth in those. If one or two of them gets struck, or joint ill, or any of the 100 things that can give them a setback, then you will not have too large an issue or cost to keep those on a bit longer, or wouldn't lose a great deal if you sent them off a bit light.
But with primitives and extensive systems, which I think would be the majority of smallholders, the benefits of keeping early, larger lambs entire probably do not outweigh the potential downsides in most cases. IMO.
(*) And the risk of escapes is usually higher with little primitive sheep too

Soays and Manxes particularly are famous for scaling walls...
