My two cents on the Hawke vs Opticron in your shortlist...
The new Frontier ED X is IMO the best build quality Hawke have produced to date. Each pair are quality control tested and a check list supplied with the binocular. The eye cups can be twisted off similarly to an 'alpha' binocular which makes for easy cleaning and replacing if they are well used. Optically they are superb but only very marginally better than the Sapphire ED. While the Sapphire was at full price, it was a no brainer as the Frontier ED X was cheaper. Now the price of the Sapphire makes it a trickier decision between the two.
The Opticron Countryman is Japanese made (Hawke are Chinese made) so build quality is superior. Lovely smooth focus wheel, lockable dioptre, very firm, comfortable eye cups etc. Narrower field of the view than the Hawkes but very sharp. Named HD+ but don't think they have ED glass? Last time I used them I noticed more CA with them compared to the Frontier or Sapphire. We don't have figures for light transmission but I'd imagine all perform similar.
Good luck :)