The only problem I see is that you stated that you do "mostly" mono editing. If you only have 1 speaker then you can "only" do mono editing.

Some may argue that mixing in mono could give you an advantage because you would be forced to use techniques other than panning to give parts definition. Then you could always get some decent headphones for $100 to do a little panning after you get your mix.

It shouldn't be a problem if you want to do 5.1? Then you already have a center Mono dialog speaker. So what you really need is 4 mediocre speakers and one good one. That and 3 pairs of amplifiers worth their weight.

Still mixing with my 6 JBL 4310's/4311's/4312's. OK, so I have two pair of KRK's also.

So really, what you really need is three. Left, Center, Right. You have two ears you need at least two speakers. Plus that center dialog speaker.

Dollarwise & speaker foolish.
Ms. Remy Ann David

I do have a pair of sennheiser hd280s. I say "mostly", because it wouldn't be the only thing that I ever do with audio, but for right now it's easily 99%. If I needed panning, then I could always use the phones. I definitely don't do surround with this. Most of what I do is editing preaching.
When the time comes that I need another for stereo, I could just buy another or a nice new pair.
That does bring another question, though...
What is the life cycle of near-fields? I'm used to tannoy reveal active 6", but they aren't on the market, anymore. Would it be reasonable to buy the same speaker in a year or two? I know a lot of things aren't that way (optical drives have a life cycle of like 3-6 months).
JJ

I have to agree there does not seem to be many products with much staying power anymore. It's the fierce competition that makes it necessary for the manufacturers to continually upgrade their products. I think (it will be a cold day in hell when you can't) you can still buy SM58's? Maybe Electro Voice 635's? But yeah, the speakers seem to change yearly. Since you have used Tannoy's in the past and mentioned a former popular model, I might recommend you stay with that manufacturer. That " British sound", goes real nice with spoken word recordings. If you get a rock-and-roll monitor, you may be less pleased with the end results? It really depends upon the preacher. Some are rock-and-roll preachers. Others are like Mr. Rogers.

Lifespan of any speaker has a lot to do with what kinds of materials are used. One of the biggest downfalls has been the soft polyurethane gaskets. They rot out in about 10 years. But not all speakers have those types of gaskets. We need the cones stiff and the gaskets soft. Oh well. Look for other types of rubberized material that doesn't look like sponge rubber. So if the Speaker Cone is part of the gasket, it may not quite have the excursion of a softer more pliable type. I say big deal! I still love my old 4310/11/12's and those haven't rotted out yet but my 4411's have. Because those had the polyurethane gaskets like my 4308's had and my L19's. Sometimes, just the gaskets can be replaced other times, the entire speaker has to be replaced. So one would hope that a decent low-cost professional monitor should be able to function for 10 years? Hey! That's better than your car and they cost a whole lot more.

JBL/Crown lover
Ms. Remy Ann David

Well...
I found a set of krk rp5s for <$200 and I think I'll just go with a pair. It will, at least, get me started. Plus, they are pretty small and my work area is small (read 2' deep desk against a wall). The tannoys, with cords, were 1/2 the desk. I could always use the krks for rears, if/when I get into surround.
JJ

Surround sound preaching, what kind of church is this?

The sermons we have, I slap a soft-knee compressor on, and run off an mp3. I ride the fader (a knob really) on the way in. That's it. I barely touch EQ or anything, although maybe I should...

That said it sucks to begin with. Borders on feedback with the PA system. Not to be advertising but if you wanna hear how bad it is, see(Dead Link Removed)

Hehehe...
The surround was if/when I ever get into audio for video.
And, as far as audio editing is concerned...
We record raw audio (in my instance, a direct line from the wireless receiver), then do noise reduction/compression/etc... in post-production. Then, take out coughs/ticks/stutters/annoying people in the crowd/etc...
After it is all mastered, then it goes to cd for distribution.
We also do mp3s, but that's usually of the main mix, without processing or editing.
JJ

Well...
I went with the pair of rp5s. I got one a week ago and the other is back ordered until the end of July (Eeek). I currently have the 1 rp5 on a shelf, directly above my screen, upside down and on an angled isolation pad. The tweeter is aiming pretty much at my head (just a tiny bit above).
Since I'm doing mono editing, it seems to be working out well.
Remy...
I've seen you recommend the rp5s at various times and I must say that they are a good fit in my setup. The shelf is 1' deep and the speaker pads are right at the front edge of the shelf. There is still about 1" to the wall for the cables to bend, so they aren't crimped. I can't say for their mixing ability, but I've edited with the one for a couple of hours, now, and it seems good.
One thing that I noticed, which is good, is that it's not as rumbly (that's probably not a word) as the reveals that I'm used to. We record a direct line from the wireless receiver and I've always found the raw voice to be boomy. Eq isn't my stage, though, so I've just lived with it. The 5" speaker does a good job of masking it. The raw voice sounds more natural to me, now.
JJ