I love the look of the taller tiers but I am wondering about support with these. Can I have 6-inch tiers and still use SPS? Also, for those who have done these taller tiers, have you ever had a tier start to cave in or collapse on itself because it is heavier than a regular 4-inch tier? I just don't know if I have a 4-tier cake all 6-inch tiers if I need to be doing some additional supports in the tiers to make them sturdier.