Photo safari

I was back on the river at sunrise to take part in a 'photo safari' excursion (well, I wasn't going to pass that one up, was I?)  It was a great experience and we a saw wide range of birds, several crocs and lots of buffalo, baboons and impala.  

The 'safari' boat was a specialist set up with 360 degree swivel chairs and 3d gimbals - which were needed to support the impressive sigma 150-600mm lens we were using.  Those of you who have seen the London blip I posted earlier today will surmise at this point that I have my eye on one of these beauties.  

Yes, well, hmm.

It's surprisingly affordable as these things go and every review I've read since I've got back has been glowing. 

But:
It's a big boy and needs a tripod or at least a monopod for any 'handheld' pretensions.  I would also need another camera bag with a different internal layout to accommodate it - both of which push up the overall cost.

It's one of those bits of kit which is tempting in terms of picture quality but I do question how much I would actually use it over a period of, say, 5 years.  Any thoughts?  Does anyone out there have one of these lenses or other recommendations?  (I already have a very good 70-300mm).

The rest of the day was spent queueing to cross the border into Zimbabwe (a straightforward but slow process which took far too long) and then travelling to Victoria Falls.  Check in was chaotic, not least because this was our final destination and we all had different onward travel plans. I dashed down to the national park to see the Falls and try and do a bit of gift shopping on the way back, before the joining the group for our final dinner together.