The other bugbear I have with the comparison between NHS and private biomeds is that in the NHS we are required to work on a fantastic variety of equipment types and models, Whereas most private biomeds who work for major companies tend to work on a fairly narrow range of equipment.
Bug-bear? "We Specialise in Everything"!

But you may have a point, as (thankfully) we are by no means a "major company".
I hear what you're saying, Bill, especially if a tech is working for one of the manufacturers. But sometimes the opposite is the case, especially for independent (or third-party) service providers. For instance, you must look after a lot of infusion pumps ... but how many different types? Two, or three perhaps. Whilst I (for instance) can see pumps from at least five different manufacturers staring back at me on the shelf. Coupled to that is the fact that all our guys (being what you might call
greybeards) are all ex- this or that, and are therefore willing and able to have a crack at anything. And, indeed, do ... on a regular basis. That's just the sort of thing that appeals, to be honest (that is, the scope for inventiveness, and the variety).
I appreciate that this thread is about the NHS situation ... but as the
Dark Side has been mentioned, let's not forget that it is also quite diverse, and generalities may not always apply!
No "Pay Bands" and such here, either. It's a question of:- here's a job if you want it. And this is how much* we pay. No increments, and no pension either. You might have better luck negotiating a more interesting "package" with one of the Big Players, of course. It all depends what a bloke is looking for.
3,000 different types? Somehow I doubt that figure, Bill. My money would go on around 800 tops.
The "real worth" of the in-house biomed is just that. In-house. Minimum response time, familiarity, continuity
etc. 
@Sean: seeing that you introduced this topic with a post about a perceived squeezing of pay bands, how about (for the benefit for all of us - many - outsiders) putting a salary range against each of those Bands and outline "personal specs"?
*
The "going rate", in case anyone is interested (around Band 5, I should imagine). And we're still looking for "volunteers"!