I have heard Walsh 2000's, and actually owned them! I have also owned Obelisk2's as well, currently own Duevel Venus, so I am an omni lover in general. Going back to the Walsh 2000's, mine were an upgraded pair of original Walsh 2's in the older, more appealing to me, cabinets. I sent in my old and original drivers for a pair of the 2000 cans, which were sent to me and installed by me. Later on, due to moving to a bigger room, I bought once again, older 3XO cabinets and traded in my 2000 cans for 3000's.
I have also owned the Micro Walsh version as well, used as surrounds in a home theater setting with Walsh 2000's or 3000's as fronts/mains. I think the Ohms are very nice sounding speakers, I enjoyed them for quite a few years, both in 2-channel stereo setups, as well as the mentioned home theater setup, where they shine very well. Ohms due to the way they are designed, have a fantastic way about placing the soundstage, and having no real sweet spot unless you get too far out of the speaker boundary. Quite nice if you are into that sort of thing. They do a very good stage, both laterally and depth, and image height as well are portrayed very nicely.
I wouldn't call the Ohms the most detail oriented, but still very good. They are very coherent top to bottom though, and sound quite spectacular overall. They have very reasonable bass qualities, especially for the respective cabinet sizes, and here also lies the part about picking the right size for your room in order for things to sound proper. John Strohbeen, chief cook and bottle washer of Ohm, has a typical chart that takes room size into consideration. If you stay more or less within his guidance, the speaker will work very well in that given room. The 5000 series has switches than can tailor the response somewhat, so it can be placed in almost any size room, within reason. Basically, all the Walsh series have such similar voicing, so it isn't a matter of going from good to best in the lineup, it is just the amount of bass/midrange required to fill a certain room size, which I think is a very clever idea. Be aware too, Ohms do like a bit of amplifier current to sing well, especially the larger models. Class D seems to work very nicely with them, as well as some of the older, more powerful amps from NAD etc. Ohms also work a bit better closer to the wall behind them, say around a foot off. Other omnis do tend to like to be a bit away from room boundaries, although as I have found with my Duevel Venus, they can be situated fairly close as well. Like anything, there are no absolutes here. One must try for themselves!
Ohms, at least here in the US, are a pretty good buy, not terribly expensive by typical pricing going on these days, and they can be found on the used market at very cheap pricing and worth a punt. For those overseas, I only know of the German outlet, Audible Emotions, and Mathias Ertl(?) there is a really fine guy that seems to be great to deal with. He and I chatted a bit quite a few years ago.
Probably the biggest downer for me on Ohms, and I admit, maybe I am too much of a stickler for build quality. The Ohms, well, while they sound good, the build can be let down a bit. I had some issue which I will not go into, they were eventually resolved, but, they still are not up to a fit and finish like say Shahinian(but not many are) or even my Duevel speakers. Sound quality wise, I think I personally like the Shahinian and Duevel better too, but, I would still live with Ohms, so there you go. Some call Ohms "wooly" sounding, diffuse, etc. I do think the older, original drivers can sound a bit wooly, but lets face it, a lot of those will be going on 35 years or so old by now! Diffuse, well, I think we are mostly used to direct firing, monkey coffins that hurl music at you in a hyper, detail oriented way, and omnis certainly present things in a different way, maybe a bit more relaxed? I never found any of the omnis mentioned though, to ever be lacking in imaging or even detail for that matter. MBL and German Physiks are out of my wheelhouse price wise, and while I have heard the least expensive GP quite some time back, and it was really good, I have never heard any of the MBL's. I imagine they would be quite wonderful though in their own way.
Each of the designs mentioned above, go about things in their own way, and each brings their own sonic flavor. It all comes down to what you value or listen for, and if the particular design does it for you. Ohms might be a stretch getting a pair if you are in England/Europe, but could be worth a shot. I would be more apt to look at the other omni designs though, even including Larsen, which I also owned at one point in time. It may not be a total omni design, but very omni-like. I enjoyed my pair of Model 4's for almost 6 years. A pair of Duevel Planets would be possibly cheaper yet, all depends on your budget, and taste in the visual aspect, and also the sound of course. Anyway, I have blathered on for too long here, glad to try and answer any more questions if and when! Have fun! Tim
PS-Shaun, I see you are in Aussie land? There used to be a dealer there, cannot recall at the moment, that had a limited number of the Ohm Walsh models, maybe 1000 and 2000 series?
I just looked, it was Decibel, not sure they still carry Ohm though...