T&m is VERY dependent on rain. When we first began experimenting with it and the rains came, our plots did great. When the rains stopped the last 4 years, t&m was a complete failure. In the droughts of ‘11 and ‘12, we planted plots conventionally and they did well regardless when the rains finally came in November. We’ve never tilled deep, but the dirt must hide more of the seed from raiders and/or the better seed/soil contact with tilling made the difference. We will be starting over completely this fall with conventional planting, but IF the drought ends we’ll try t&m again in the future, there are great benefits to regenerative plotting.
One more note, you mentioned brassicas; turnips in particular are very dependent on nitrogen, if you’re not throwing them into established clover, they will not do well with t&m, unless you throw urea on them and get good rain within 24 hours. The urea will release its nitrogen into the atmosphere and do nothing for your brassicas otherwise.