Thanks for all your replies.
On the question of price, the current 7dayshop listings show
So on price the DO
lens is relatively inexpensive, is approximately half the weight, but the experiences quoted above are conflicting.
From all I have read in this and other threads, those A.netters who are Canon users, continually extol the virtues of the L IS
series lenses, based of course on their results.
To be honest neither size nor price are that important to me, I just want to buy the best first time and not have any regrets later.
I also want to be able to use a 1.4x converter, and as I said above, this appears to only be effective on autofocus with a F4 or better lens and only the 28-300 and 70-200 meet this objective.
Thanks again, I'll have to sleep on it!