I have no experience with the dolphin, but have owned a tiger shark for 2 years. It is used in a 33,000 gallon gunite rectangular pool. It has performed well, requiring no repairs so far. I use it an average of 1-2 times a week. The filter works well, but like all cartridge type filters, is messy and wet to clean. I still find it necessary to vacuum the pool after storms or high wind as these types of cleaners to not handle a large amount of leaves or debris very well. It is great, however, for routine weekly cleanings. It even does a fairly good job on the steps.

EricF