I have a kettle RIMS system (though the recirculation aspect of it is the only important part I suppose), and doing no-sparge I hit 72% consistently (at least that is the number I put in Beersmith which correctly predicts my output wort gravity). I was having problems where I was down closer to 60, and here are some of my observations from my system.
The crush was counter intuitive compared to batch sparging. When I had the crush finer, I had to drop the recirculation rate which didn't help for temperature control or ramping speed. When I widened out the gap on my mill, the crush was courser but the husks were more intact and the flow rate could be increased. The net effect of it was that the increased flow/agitation resulted in an increase in efficiency.
I also started doing multi step mashes (why else have a RIMS/HERMS system?), with steps at 146, 153, 161, and 170 (mashout). This extended the total mash time to more like 1.5-2 hours. Monitoring the gravity, you can see the gravity keep increasing at each step until it kind of flattens out. For example, on my last batch at the end of the 153 step, the gravity was 1.038 but by the end of the 161 step it was 1.047 with a target of 1.048. I don't know if it might help you to monitor the gravity when you are at your 158F step and see if it is still going up while recirculating and make sure you aren't cutting things off too early.
I would imagine if you are sparging you would certainly be able to get better than the 72% I'm getting with no-sparge.