I've been a little sporadic over here, so this thread hadn't come up for me (or attracted my attention) on my earlier searches.
I'll chip in what I can - seeing it's almost 1am here.
Very quickly, a bad active system will be worse than a good passive system, all other things being equal. Also, a well-designed passive will beat an active at the same price point, all other things being equal - the additional cost of amplification robs some of the attention the rest of the circuitry would have gotten. And very generally, a well-designed active will have a crossover that may be more expensive than the cost of an electronic crossover and the amps in an active system. Confusing? It's meant to be.
To put it very simply, there is no golden formula or rule to ascertain which would suit you better. You have to carefully consider your requirements, your ability to drive low-level or speaker-level signals around a room (both of which are very complex matters best left to a more technical discussion which I don't have the time for at this moment but can get into later), the intended use of the said system and the depth of your pockets.
There are advocates on both sides of the fence, with examples like the Nautilus and the Confidence on the passive side, and the Orions and the Beolab5 on the active side at the ~3000 dollar budget range, for example. None is better than the other, but they're all a little different. Active speakers do have a number of advantages - a lower number of performance-affecting variables, easier match between multiple units, more predictable performance, and a system that keeps to spec for a longer period of time. But they do need a very capable upstream system and decent power connections spread across the room. You can't put 5 sets of Orions in your living room and use an extension cord. Passive systems have more difficulty in crossover consistency, and therefore matching between units is generally quite poor (specially at the entry level), are sometimes difficult to drive, and require low-impedance connections to the amplifier, so you have to route some pretty heavy wires all over your living room.
My recommendation would be the regular passive speaker + receiver route. I know 60% of your usage is music, and therefore the ideal setup for you would have been two high quality speakers and a high-quality stereo amp, unless you are hell-bent on surround. Which it seems you are, so I'll assume surround it is - and so you need a scalable set of 5 speakers and a sub, plus a receiver to go with it.
Coming to your specific choices, I have heard the Image series but not the Alpha. The B25 are very, very good speakers and you'd be hard-pressed to find equivalent value (they cost ~25K/pr). I know the Wharfedales get more votes around here and probably for good reason, but I have not heard them so can't comment on their sound. The PSBs image beautifully, and can fill a reasonably large room with little stress. A little on the quiet side, but they disappear easily once the volume is cranked up. You need a good amp for them - they are low impedance speakers and reasonably difficult to drive.
The Mission are very ho-hum - boring, flat and uninvolving. Polite, and can sound a little stressed at high levels. Very little dynamic range, so I'm not sure will work well for movies. The Polks are just the opposite, very juicy and bright - probably excellent speakers for home theater if you want to impress the neighbors, or if you do a lot of listening at very low levels, where the excess brightness may actually help. Not polite at all, so may be fatiguing over long stretches of loud listening. I hated them, btw, but you might want to listen as a point of of reference (and to figure out how you would treat any advice that I give here).
The issue with studio monitors is that they are totally unsuited for music listening unless you're a mixing engineer trying to analyse recordings for techniques and tricks. If the A5 sounds like it, I'd stay far away if my intended use is music and movies. I have covered some of the pitfalls of this approach earlier, search my posts.
However, the A5s are targeted toward music listeners so I doubt very much that they will have the response of a studio monitor. Since they clearly state that they are "not designed to be up-close nearfield studio monitors", I am pretty sure that their crossovers are optimised for mid/far field use. Again, I have not heard these but if it was a serious monitor (with all its attendant defects for regular room usage) it would have merited some attention in the pro circles, of which it has none, so I can safely assume it is a "room" speaker and not a "Studio" speaker. It should therefore be usable for HT duty.
As far as the receivers are concerned, I'm afraid I can't help you there. Maybe some of the other guys will have more inputs for you.