I'am pretty new to DWC and I haven't used those sure-to-grow cubes, they look legit though.
You def dont want to give seedlings nuts. If anything maybe a tiny bit of thrive a live or superthrive.
I like Olivias cloning solution.
http://www.oliviassolutions.com
Ok, this is just my experiences and not everybody has the space but I prefer to make or buy clones in rock wool.
I've used bare root clones, sprouted seeds in a variety of mediums/methods and made or bought clone in a varrity of mediums. This work best for me.
I use a white propagation tray (
http://www.hydroheadquarters.com/standard-flat-white-w-o-holes/) with humidity dome (
http://www.hhydro.com/Nursery-Dome-Tall.), and depending on if they are for soil or hydro I use the 50 count oasis cube sheet or the 102 count oasis tray with wedges.
I like the 1 1/2 50 count cubes for hydro because they are easy to just set on the medium and pour more medium around them by yourself.
Rootcubes 5015 Medium 1.5 Inch (not a link)
I like the 102 count tray for soil bc the root can pop out fast with the small size of the cubes and they are easy to separate from each other.
http://www.amazon.com/Oasis-OASIS-TRAY-102-WEDGE/dp/B004FVLHDE
When using the 50 count sheet in a prop tray i place the sheet of cubes in a tray with "holes" or "slits" in it like this
(
http://www.growsmarthydroponics.com/propagation_trays_10_x_20_-_with_holes.html?utm_source=Google&gdftrk=gdfV22646_a_7c984_a_7c4625_a_7c726167) .
I then place that tray into another prop tray of the same size with a layer of perlite in between them.
This helps regulate humidity and prevents over saturation.
When using the 102 count tray with wedges I place a small layer of perlite in the prop tray under the plastic which houses the wedges.
Always use a seedling heat mat to speed things up.
For me 100% of cuttings/seadlings survive 100% of the time and when they hit the dirt or water they have decent roots to take off with.
Most strains root (and i mean sticking out if the cubes all over) in 10 days