I have a theory about this texture business, because my DD is the same way or was until just a week or so ago. I think that when babies are eating finger foods, they know that they will have to chew them. But with purees, they don't expect lumps, and when they get them don't know what to do about it. Even though they are softer lumps, it freaks some babies out. I think you just have to go nice and slow and keep trying. That's what we've done. Also, you can buy a stage 2 and stage 3 dinner of the same variety. Feed bites from the stage 2, and then give one bite of the stage 3. Alternate as much or as little as your baby will tolerate.
And I don't know why your LO would refuse the porridge. Do you make your homemade with other stuff that isn't in the baby jars?