I am not impressed with the kenetrek boot grease. Doesnt seam to do a dang thing, my boots didnt start to crack until i started using it. Picked up some snoseal this year and it seams to work very well.
Crispis get the special Crispi juice.
Everything else gets the Kennetrek wax.
As for the rand issue - my tibets suffer on the toe but I blamed it on hooking sharp rocks and a horse stepping on one.
Sno Seal contains bees wax and light petroleum distillates (per the SDS), the latter acting as solvents on glues used to adhere rands, similar to how kerosene can remove goop and glue. The solvent properties of Sno Seal is why most manufacturers recommend non-petroleum-based sealants. A petroleum solvent residue on leather would definitely reduce adhesion by glues. That said, Sno Seal is arguably the best waterproofing for straight leather products such as work gloves, though I've heard Mink oil is excellent.
I've used Obenauf's sealant on my Tibets for a good year of Alaska hiking and abuse. It soaks in well, but doesn't prevent wetting-out of leather. Obenauf's contains "oils and beeswax" per their description and I heard second-hand that some boot manufacturers don't recommend the use due to oil content. I applied Obenaufs to dry, clean boots.
I'm going back to Nikwax (formula in a tube) for a while to see if water repellency and durability is improved. That said, my boots are going on season 5 of hunting in crap conditions and holding up well. I will apply to wet, clean boots per the instructions.