Had DoelFins fitted on the 90 yam/5.4 sr when received. Removed them, and in my opinion the boat handles slightly better without. Can trim the engine more now, won't put them back. Impact on speed was not significant.
On the bombard SIB have smart tabs, and during water sports there was a huge positive difference. Instant plane on very low speeds and only minimum bow lifts. But so far no plans to put smart tabs on the SR. Might consider a manual jack plate but thats another story.
fun on a boat is inversely proportional to size...sort of anyway