The accuracy of this system, how easy it can be used to create recipes/pipelines with limited or no programming experience - just by using drag & drop! I dislike that you cannot select multiple items at once in order (or sort) so if there are more than 2 ingredients needed then manually sorting them out as they come up would have been easier!! Not really anything about Prims per se but rather our requirement was an accurate piece-of-cake solution which could feed into several other programs we use daily without any problems from having different interfaces etc between those applications.
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