Burn the heretic!
In all seriousness, if this were available today, I'd probably buy one for shooting the Papal blessing on our Europe trip next month. It isn't, though, and I'm not about to buy the current-generation dust sucker, so I guess I'll just stick a TC on my 70-300L to make up for the loss of reach resulting from my FF upgrade. *sigh*
It is not a "dust sucker". Many of us in the forum do actually use the old lens and know its strengths and weaknesses. Dust penetration is not generally a problem.
5D IV, 5DS R, 7D II, EOS-M, Powershot G3 X, 400mm DO II, 300/2.8 II, 1.4xTC III, 2xTC III, EF 1.8 STM, EF 70-200/4 IS, EF 24-105, 15-85, 100-400 II, Sigma 10-20, Sigma 150-600mm C, EOS-M5 15-45, f/2 22, 11-22, Samyang 8mm f/2.8 fisheye