Personally, I feel that OHPW (which is now named Critter Love Original) is better of those two. If you feel instant is the best way for you to go, consider Critter Love Complete, which is also instant, but better quality, and was created and tested by the same person that created the Original HPW.
Also, pellets are not bad to serve as a side to a reputable diet. If you decide to go with EN Instant HPW, than please follow the diet as directed as should be done with any diet you choose.