Personally... make it a Level 1-15 character maximum and welling level 25+ Whites (remember, you are talking about a group of 5 and not solo on Softcore).
This will give you &/or them a chance to see how their low level gear actually makes a difference, also, those that DON'T use + Max life gear should just give up.
I well at level 1 Tier III / IV items on HC SOLO... this should not be an issue for the SC 5 man group welling.