Damn, don`t remember all those tube descriptions from the head anymore
But... Mullard PCC189 is similiar to 6N23P reflector. Smaller type, intimate & warm soundstage. Should be good for blues but don`t listen to it much. Try to search more of my comments about this tube. And btw, there are 2 different types of Mullard PCC189, one is yellow old style logo and another is white old style logo.
Versus Ultron - no competition imho, Ultrons are way better. But this is only my opinion. Mullard PCC189 should be quite hard to get from eBay cheaply.
e: I would search for Philips PCC189 (Holland). Unfortunately all those philips`s I recommended are gone.
e2: oh, wait, you already have orange? then Philips PCC189 is not worth getting. Tubes that I personally consider to be in "orange league" are Amperex GAC, Ultron PCC189 and Miniwatt-Dario PCC189.
Maybe it is relabeled pinched waist amperex xD
Btw, it`s not pinched waist but pinched base! Glass looks something like this: http://www.tube-classics.de/TC/Tubes/SieTel%20ECC81/ECC812.jpg
One more difference between gold label ultron and white label ultron - last one has copper pins inside tube. Gold label has metal pins. Also , my white label ultrons have A letter pressed on the inner side of the glass bottom.