Fundamentally, executing any dynamic maneuvers creating high loads (spiral, dynamic wingover etc) with opened trimmers is dangerous!
Releasing the trimmers shifts the loading center of the canopy towards the leading edge.
This rule is valid for all paragliders, but the more reflex traits in a profile, the more radical the effect. In a typical reflex paraglider (Nucleon for example) the load distribution after releasing the trimmers looks like: A row =60%, B=30%, C=5%, D=5%.
Carrying that much load by the A and B rows of reflex paragliders (90% in total) offers us the stability we so much crave. On the other hand, however, when coupled with a dynamic figure like a spiral it can move the load dangerously close to its maximum values.
More on the load distribution in various paragliders at diverse riser configurations you can find here.
Analogous situation emerges during execution of a spiral or wingovers with big ears pulled. Here again we have the entire load concentrated on reduced wing area and this, coupled with aggressive G-load maneuvers, shifts the singular loads too close to the maximum values again.