First of all, nice collection- not all to my taste if I am honest but I wish I had a garage big enough to keep them all in (mine is like a jigsaw puzzle of bikes and tools) and a great review of each too.
I think as others have said the earlier bikes may feel rather small compared to your existing bikes (and indeed to almost all current large capacity models) but they do seem to 'fit' a varied size and shape of rider pretty well although the handling may feel quite 'sketchy' to what you have become accustomed to as well.
Also worth bearing in mind is that out of all the original shapes the 'easier to live with' fuel injected models are getting on in years now and will almost certainly need more attention to keep in good order than a newer modern bike. This fact is even more apparent if you decided to go for an even earlier bike with carbs- they don't really like being left too long and aren't so much of a 'hop on and go' kind of bike.
What you do get though is the start of the Monster line, an undiluted, very 'organic' riding experience with only around 80 bhp. 180Kgs and no rider aides what so ever. With the suspension sorted and decent tyres you feel everything going on underneath you not to mention ease of maintenance and relatively low running costs (especially if you do your own servicing) along with a bike that has most likely plateaued in value and may well be on the increase if investment is your thing. It isn't mine- bikes should be ridden not just looked at.
And I think that is why there are so many long term owners or people who have owned them in the past returning to those early bikes so you probably should try one anyway even if it is a case of 'never meet your Heroes'.
On a personal note, even after almost twenty years of owning my 900 I still love it as much if not more than ever. It doesn't get ragged these days quite as much as it used to but holds it's own on the right roads as well as still looking (in my opinion) bloody lovely, which when I pop in the garage on those rainy days when I don't want to ride is enough to make me smile.
