Composición Colectiva VII: O-ir Mortales [Collective Composition VII: O-ir Mortales]

Hi Spa, thanks for your comments. This is what I've used for each of those projects you mention:

Electroacoustic Infestation:
I used 6 Mackie DLM8 with a subwoofer (DLM12s). More information here.
Yes they are a bit expensive. They worked pretty good with spat~, I was using VBAP then. I am not a fan of they sound quality but since they were located at that height (close to passers-by ears) I didn't need them to be super accurate.

O-ir, Mortales:
I used studio monitors called HSR 2.5. They are pretty bad monitors in my opinion, and the results were affected by that, but I had nothing else at hand by then, so I used them. Again, since I wasn't using the Z axis (up and down) I decided to elevate them to ear's height and keep them close one from the other, is was a good solution to make things better, I also used VBAP and spat~ since gave me better spatialization Thant ambisonic.

Kitchen Bells:
Well....they are a collection of discarded speakers. I just went to a second hand store, bought whatever speakers I found, remove them form their case and hung them. Since that piece has a lot about acoustic ecology, recycling I didn't care much about sound quality. I wasn't using any spatialization software then, they reproduced audio straight from the audio file.

So, for your question about monitors, yes, according to my experience using monitors for ambisonics and VBAP is best. Indeed their power may become an issue if you are trying to cover large areas, then you either need more or larger speakers. The bigger field the speaker has the better, that's another problem with monitors as you mention. In this project I used eight Yorkville YSM5 monitors, in an ambisonic cube configuration, they worked ok but I think I separate them too much one form the other (about 8+ meters away), they would probably will work much better up to 4 meters or maybe set up 16 instead of 8. I guess what I am trying to say is that monitors are better than regular powered speakers (indeed quality affects your spatialization) but they just work in short distances. Regular powered speakers will be better when you need them to be spread (as I did here).

Oh yeah, I always use a sub for having better quality in the low end, normally I try to put a FQ cut on the monitors so they don't over work, but that not always work (it depend on the hall, speakers quality, etc).

I'm sorry, I think I'm not helping you much, but I hope I am giving you some useful guidelines!