there really is nothing to changing the resin in the refillable blue containers, takes a couple of minutes to change
Sorry but no way does not take "a couple of minutes" to change the resin a DI bottle. I use them all the time, you have to detach it from the system, empty out the resin, rinse it out, then carefully feed the resin in around the riser tube, which is an art in itself (that stuff gets EVERYWHERE) and when its wet it sticks to everything.
Then you have to rinse the whole thing down because without fail the resin gets all over it.
In my experience it takes a minimum of about 40 minutes.
(And even longer if you forget to put the riser tube in before you put the new resin in)
Have to say I have been very tempted to convert to ionics filters just for the "clip off, clip on" convenience.