It's not that bad. Archifiend and Meteor versions would be too OP for this 4k LP mode. Too much direct damage.
Red-Eyes Slash Dragon is more balanced, plus it can cancel cards like Enemy Controller and Order to Charge :)
Plus you can combo it's effect with other equip cards that benefits you when destroyed by a card effect, such as Smoke Granade of the Thief or Black Pendant.
Slash Dragon is not that good without Red-Eyes Fusion. If we had at least ONE copy, it could also be searched by the third copy of Red-Eyes Insight, since it has only Red-Eyes Spirit as target (limited to 2)