Obiwan:
That's quite a respectable distance from the wall I think. Assuming you are planning to put any new kit in the same spot I think you would not have to concern yourself with front or back loaded ports so it does give you quite a bit of choice.
As to whether to go for a bookshelf design or a floorstander design I think that your personal preferences and the execution of the speaker itself will be of greater significance to you than any advice I can offer. Vague answer, I know, sorry.
However...as you most likely know, with metal there is not so much of the 'electronic' bass that you get in pop music for instance (think Lady Gaga for example) but one thing all 'metal-heads' love are those double kick drums. Given the intensity they are hammered out (Armory and Gloryhammer are good cases in point) I personally think that offers two alternative general approaches:
A: for a modest to medium budget a good set of bookshelf speeakers will have the speed and punch that gives you all the joys of delicious metal. I wouldn't really think about floorstanders unless...
B: for a 'high' budget (I'll let you figure out your own limits): really good floorstanders should offer something like the speed of bookshelves but with an extra dose of disemboweling slam that feels awesome (how acutal disembowelment can feel awesome is beyond me but at least it sounds cool).
Forgive the presumption but I saw earlier in your post that you listened to the Monitor Audio RX6, if that is the price range you are thinking about I would probably be more inclined to look at a bookshelf/monitor over a floorstander but that's just me.
It wouldn't hurt to give the R300 a listen but if the opportunity arises to try out the new 685 I would certainly give it go before commiting.The Dali Menuet (sp?) is also a very nice little unit if you are feeling adventurous.
I'm afraid I haven't had the pleasure of listening to your amplifier so I cannot make any worthwhile comments there. As a matter of curiousity, do you have any friends nearby who may be willing to lug speakers over to your place to see how the presentation changes (may require beer/pizza/movies
)
May the force be with you. Or is that "These aren't the droids you're looking for":?