No, you wont.
A well set up vee with good pads will be just as good as any magura (better, in my opinion) and you'll not need evo mounts, that frame's had some 4 bolt - vee converters bolted on, just take them off and put the maggy with normal 4bolt clamps on if you wanted to go down that route.
Smart bike (it's definitely an 04 Pitbull, as has been said previously) change the rear hub for a pro2 and find a bar + stem combo that feels good for you and you'll be sorted for a fair while to come. No problems at all with a sprung tensioner, you seem to have a sensible outlook on everything - do what you think's right and i'm sure it will be