I have often used Ilfors PQ universal developer to process B&W films. I have tried it at 1+4 for 4 mins @20C and the resulte were very grainy on Tri X film. I also tried it at 1+19 for 8 mins on Tri X and it showed less grain. I even tried both of of the above on two films in the one tank a HP5+ and Tri X and again the results were the same.

Years ago I worked in a wholesale lab and if they ran out of D76 they would use Ilford PQ instead and all films were given the same time.