it has been variously described.
Variously described but without the possibility of it being shared by anyone. What would make sense is if this "sudden insight", this "self realization", this "divine revelation", this "act of grace" could be given a physical manifestation like a book explaining what these actually mean. Now that would make perfect sense.
The experience is intensely personal and indescribable
Unfortunately, an intensely personal and indescribable experience is just that. Indescribable. Who knows what the guy is feeling. It might be a seizure for all we know, as long as it remains indescribable. It needs to become describable like it became with the Prophet Muhammad (saw).
In this state God is nothing but pure absolute Love
I have no clue what that means. Do you? I don't want to call it mumbo jumbo but I want you to explain. If you say that it is indescribable, I would get your head examined. For eg. when I say that I love my parents, I don't just talk about it, which is what these sufis that you admire seem to be doing. First, I believe that they are my parents. Then, I try to make them happy. I try to do what makes them happy and avoid doing that which would make them sad. And I do this not because I expect them to give me something but because of that which they have already given me. I don't just claim to have achieved "self realization" and leave it at that. Similary, if you claim you love God, then do what he commands you to do. Don't do it for heaven. Just do it. But no, that is not the kind of God you want. You want a God that you can love, but one that you don't have to do anything for, except "love" him which means nothing more than mumbo jumbo.
Rabia Basri about hell and paradise
First, who is Rabia Basri? This might be a question for ghulam muhammad. Which religion did she believe in? Did she believe in Islam? How did she believe in Islam? Was it from the quran and the sunnah of Prophet Muhammad (saw). If she believes in the quran then does she agree with what the quran says about heaven or hell?
Besides, Rabia Basri's quote about heaven and hell refers only to the believers. It does not include the disbelievers. And she doesn't say that there is no heaven or hell. She just wants the believers to believe without fear or greed. But we are talking about those that don't believe in God.
Regarding, "more than that", please tell what is it?
More that that is what you don't like about religion. Salah, Roza, Hajj, Zakat, Quran. These are the things that complete Islam. Without these things, you have nothing more than a seizure.
Now, coming to those that do not believe in religion but believe only in God. Do they believe that it was God that created the earth and the universe? Do they believe that humans were created by God? Do they believe that God has a plan for all humans? Do they believe that this God helps people who ask for his help? How do they ask for this God's help? What about those that do not get any help? Why won't this God help them? Unfortunately, these sufis won't be able to answer any of these questions. If they could, these answers would be noted down in a book from which others could benefit.