From my few years of farming Guava , it really is not a matter of cloned or traditionally layered/grafted plants that matter but the authenticity of the nursery. With no certification process or record of how the plants from a certain nursery have performed we are really at their mercy. Remember they are in business to sell the plants , what happens after 2 years is up to us.
So if you know the nursery well go thru their whole production process, check where they are getting their mother stock from, visit as many farms as you can - where their plants have been supplied. Go to farmers whose location is similar to yours and get a feedback before going ahead with the purchase.
They will be able to tell you better what issues you can expect from the plants coming out of that nursery