I have a Hay King Brand pasture renovator and use it annually. I have Houston Black Clay and where I run the coulter/shank combo the ground cracks open this time of the year and some of those cracks can get wide and deep...like I have found some over 6' by late in the year.
Part of my place is on the side of a 1/5 hill and I contour plow with it. The cracks capture the moisture and nutrients, including grass clippings (humus) that would otherwise run off. As far as cracks being a problem, yes they make for rough ZT mowing along with clump grass outshoots but as long as there is moisture in the soil, which you captured over the winter, you don't have much of anything, especially where you have a grass covering. What cracks out is mainly where there is sparse to no soil covering.
The other thing with the renovator is that it has become my primary crop preparation tool for annual crops like sudan-sorghum haygrazer. Deep (clay) penetration is accomplished followed by a 3 pt. rototiller and a spike toothed flexible harrow....3 passes and ready to plant. Perfect seed bed and good penetration for plant rooting. I used to use a rolling plow, disc harrow, and spike harrow but it took twice as many passes and results were far less desirable than what I get with this combo.
On being too late, depends on your aspirations. If preping for a winter or next year's crop, good time to go at it as the clay (for me) isn't rock hard yet like it will be later in the season.