Patience is a virtue.

Those Cube bikes are certainly lookers.

I think you should rule the 8.3 out straight away as you are almost certainly right that it won't compare well to your Hyde.

Whilst it won't break the bank to gain equivalency here, the Cube comes standard with 44mm wide tyres and the Trek's 38mm, so that might influence you a tad as well.

Knowing that the Cube is a quality bike, I don't think I could go past the higher specs on the Cube unless it was substantially more expensive.

Another thing to note is that there appears to be a difference in the length of the handlebars, with the Cube's being 660mm and whilst Trek doesn't state the length of their handlebars on the 8.4DS, I believe it is about 600mm.

Also, I don't know whether you meant to do this or not, but with the Trek's, you linked to the 2014 models, not the 2015 models, so I am not sure if you have seen the 2015 models.

Your sizing estimates seem pretty good to me.

I'd test ride the 2015 Trek 8.4DS and see if it blows you away, else go with the Cube.