I play a lot with Mk V on at least one side of my many blades (usually the backhand for the added control). Yes it is slower than one of the Rakza's I usually have on the other side but that does not represent much of a problem if your loop is spinney enough. I find it pushes more predictably and is less susceptible to incoming spin than the newer rubbers. Remember MkV has a hard sponge so it doesn't provide the needed speed until you drive it hard with the proper technique. Is slowness comes from the soft rubber which is where it gets its spin. So whether this fits for you or not depends mainly on your style and form.
I also have a Sweden Classic (which is a pretty slow blade) that I purposely put MkV HPS on one side and Valmo on the other to see how faster rubbers would work with a slower blade. They are both much faster than MkV original and with the slow bat function well, very similar to my carbon bats with the Mk V on the backhand, so you might want to consider one or the other if the MkV you try feels too slow on that All Around bat you are holding on to.
Having tried both approaches (slow bat/fast rubber VS fast bat slow rubber) I would go with fast bat and slow rubber, like a Ma Lin EO and Mk V (which you can get for under $100). But my style is fast close the table and I myself am moving towards even more speed (more fast bat/fast rubber) and that may not be what you want at all.
Also Yasaka has released a new rubber called Rigan, which is meant to bridge the gap between classical rubbers and the modern sponge. I haven't tried it because I can't find anyone selling it yet, but it may be worth a look as a fast replacement for MkV.