The midbass below 100 Hz is very important to the sound, satellites that cross over at 100 are always supposed to be used with a sub. It's lower down that subs become optional, there are few music fundamentals below 37 Hz, basically pipe organ, bass drums, a couple of oddball instruments.
Yes, you will get more depth as you move them out from the front wall of your room, it will keep increasing all the way to 15' out from the wall! This is true of any speaker for the same reason -- you're delaying the reflection off the wall, and the ear gauges room size by timing the delay between the direct sound from the instrument and the first reflection from the walls. Forex, if you're 10' away from a trumpet in a small room and the walls are only 5' behind the trumpet, the wall reflection will have to travel only 10' more than the direct sound, so the reflection will be delayed by about 10 ms. But if you're in a big concert hall and the wall is 15' behind the trumpet, the reflection will have to travel 30' more than the direct sound, and the reflected sound will be delayed by 30 ms. The brain detects the delay and tells you that the room is bigger. So in a small room, you want to delay the first reflections as much a feasible, otherwise the brain will detect the small wall and assume the space is smaller.
Anyway, the issue here is that the MMGW's are designed to work on a wall. If they aren't on the wall, you may get a response dip between the top of the subwoofer's range and the bottom of the MMGW's range. This is because they are designed to use the wall boundary reflection to increase bass response. Picture an MMGW mounted on a mirror and you'll get the idea -- the reflection will make the MMGW seem twice as big. The same things happens to the sound, it makes the speaker acoustically twice as big, which with dipoles gives you lower bass.
OK, so I see two possible solutions. One is to mount the MMGW's on the side walls, not sure if that would work in your case. The other would be to get the MMG's, which are designed to sit on the floor. You can pull them as far out into the room as you want.