Bass will be more manageable from a standmount, and the only benefit from a floorstander for movies is SPL
As always hanging on yr every word. If u have a moment, this sunny morning, I would welcome elaboration of these comments.
Firstly, SPL. We know that more drivers means higher SPL, so a floorstander will usually play louder than a standmount speaker - s standmount will usually be a two-way, comprising of a mid/bass driver and a treble unit. There aren't too many three-way standmounts around, the KEF R300 being the cheapest one I can recall right now. Floorstanders have the cabinet space to utilise more drivers, so you will find more three-way - and even four-way - floorstanders. These will obviously play louder, and will normally be more efficient too, so don't need as much power to drive, but as I say, they do need the benefit of a better controlled amplifier.
When I mentioned earlier about the standmount vs floorstander argument, many people will prefer the simpler design of a two-way standmount speaker to an overly complicated floorstander that might be a three or four-way design. With a two-way design, the drive units are quite close together, whereas with a larger floorstander that might have a number of drive units (maybe four or more) spread over a wider area - some speakers can have drive units as far apart as 1 metre - which can introduce many negative effects which can be detectable by the human ear. In short, the end result of treble/mid/bass can end up sounding detached, and lacking the focus of the smaller standmount.
Managable bass. As we know, standmount speakers generally don't reach as low as floorstanders. Small standmounts will probably reach around 70-80Hz (usefully), larger ones maybe 60Hz, but floorstanders will be able to reach down to around 40-50Hz (usefully). By "usefully", I mean that any ratings measured at -6dB aren't going to be of any concern, as -6dB is not only half as loud as all the other frequencies you're listening to, but they're half as loud again, and obviously, not much use to anyone.
The most predictable speakers in any room are small, sealed standmount/satellite speakers. Obviously with no port to worry about, there is very little interaction with the room boundaries, so you can place this type of speaker in almost any room and get very similar results. Problems will start to kick in with ported speakers. The port WILL interact with room boundaries, so more careful placement is needed. If the speaker can be pulled clear enough from the room boundary for it not to be an issue, great, but that's not usually possible. The other issue here is that if you pull a ported speaker far enough way from a wall for the room boundary for it not to make any impact on the sound, you have then removed part of the design that makes the speaker sound the way it should - it needs the room boundary to some extent to sound the way it was designed. Manufacturers provide foam bungs to place in the ports to stifle the air flow when they're placed near a wall, but this problem you'll have here is that this will make a ported speaker sound like a sealed speaker. The bass driver in the ported speaker has been chosen specifically for a ported design based on its natural characteristics, and has been optimised to work in that design using the crossover. If you then "bung up" the speaker and make it behave like a sealed one, you've then changed what you're asking the speaker to do, and it won't sound the same. I usually find ported speakers sound lifeless when they're bunged. Some manufacturers may provide a two part bung - one where you can take out the centre of the bung. This will have the desired effect of calming down the port's air flow, but it won't fully stop it, so the speaker still sounds the way it was meant to. Anyone currently using a full bung, I would recommending getting hold of a two-part bung to try out, or make your own if you can.
Floorstanders, which are more than likely going to be ported, excite far more room modes than standmounts. Most bass issues are going to be under about 70Hz - the area that will usually be dealt with by the subwoofer, if you follow THX guidelines. As an example, our AV demo room has a massive dip around 50Hz (not too dissimilar to my own room), and two large peaks either side of it, so around 40 and 60Hz. People who like to use floorstanders will usually have this area covered by the floorstander, and bring the sub in around 30/40Hz (depending on the capabilities of the speaker). This will also apply to people with larger floorstanders who rely on the receiver's inbuilt room EQ, as bigger speakers are sometimes crossed over around the 40Hz mark, which is an are that most AV receivers don't apply EQ to.
So using smaller standmounts with a crossover point of 80Hz, and allowing the sub to fill in everything below, allows the user to use a sub EQ system that will remove most room issues by only needing to apply EQ to one speaker - the sub. The rest of the speakers can then be allowed to do what they're supposed to do, without being messed with.
From here there's the whole argument about room correction, which I won't go into, but the first thing to do is to get the flattest response from the speaker package before asking the room EQ to mess with the signal. Obviously, the less you mess with a signal the better.