I got a blueline and its not old technology, prochem or not, sounds like a negative rumour.
Buying your first truckmount, makes you think of loads of strange questions/things, but once you own one you realise that those things you were panicing about are long forgotten.
All start entry TM's are about the same in power, if you consider that you are using a portable and moving to a TM, its a bit like cracking a walnut with a plastic hammer and now you got a sledgehammer.
What I would consider as you most important question is what TM, to where you are in UK. who is you nearest supplier. I know that Alltec will service all TM makes, not sure if this is the same with woodbridge, prochem, HM.
my advice (IMO), only get prochem if you local prochem dealer does TMs, the local prochem dealer in norfolk is crap, so TM service is crap, a week to turn around and no one knows sweet FA about TM's.