Hi,
My understanding of the DPF removal and the new MOT rules, is if it had one from the factory and it has been removed then it will fail. BUT its how the MOT tester will know what was fitted from the factory, as an example my A4 was available with or without a DPF, this info can be gained from the PR codes generated by the chassis number, but I don't think for one minute that the tester will have access to this information for all vehicles unless the logbook format is changed to reflect one being fitted. Then the question would be asked will it only include new cars from a certain date.
If I was looking for a DPF delete I would be looking at just gutting the DPF canister with the suitable software deletion, then for all intents and purposes it would appear that the filter is still fitted.
I think the rules they are bringing out recently are an attempt to combat what DVLA perceive as fraud as vehicles now have to be certified as regards to their emissions to qualify for lower road tax, by messing with parts of the system that affect the certified emission levels you are effectively altering and increasing the emission levels, therefore paying cheaper road tax than the changed emission levels would dictate.
ultimately its your decision but if the DPF system is working, then leave it alone until you have to make the decision about removing it.