Hi Rosenthal311.
Welcome to our Mattress Forum! 
I am sorry that the Vi-Spring hasn’t worked out for you and that you could not find a way to make it work… the good news is that there shouldn’t be any reason to prevent you from passing on this great product to your son. It’s using only ultra-premium and safe materials and can be very suitable for a child.
Generally, growing children do very well with a mattress more in the “medium” to “medium-firm” range, due to their epiphyseal plate and postural formation. Babies and infants will generally need a firm to extra firm sleeping surface while toddlers will generally need a medium firm to firm sleeping surface and older children that have transitioned to a larger mattress and are out of the crib will generally do best on a medium to a medium firm sleeping surface. There are also some general firmness guidelines in post #2 here for choosing a mattress for a child in different age ranges that may also be helpful. Vi Spring is a super-premium mattress certainly using very high quality and natural materials that you can certainly invest in the wellbeing of your son for many years to come.
Innerspring/natural fiber mattresses are the most ventilating, humidity controlling, and temperature regulating mattresses available and have a unique feel because of the natural fibers (which are performing differently from foam)
I am looking forward to any updates you might have about your son’s transition to his “big boy bed”
Phoenix