Two Monitors Vs. One. Worth It Just For Stereo?

Generally, the "Is it worth it" question is a subjective one.
That said, I do have a small percentage of sounds I use which would really benefit running twin DXR10's.
U2 type stuff.

Personally, I'll say it like this, I'm constantly keeping my eye on another DXR10 should a good deal present itself.
Necessary? Probably not, but I guess I'm simply like that.

For me personally, it is 100% more enjoyable for ME to play in stereo.
But I have always wanted to do that.
I am the only guitarist in my band (covers) and have to cover a TON of ground, and stereo sounds with effects are crucial to me being able to
sound as good as I want to.

Other side of the coin: A guitar cab is a mono source. A second monitor is not necessary

Agreed with carsnguitars. Of course if\when you use stereo fx the sound and your feeling in the room will change dramatically. Is it worth it? Mhhh... can you spend the money for just your pleasure? This is the real question IMO

I guess you're just looking for a justification...

Ah, ok. My philosophy on stage is to not mess with the overall sound, and less is better the more people are acting IMO. Of course I'm aware of thousands acts where the guitar goes stereo, but I prefer to keep things simple. A stereo guitar onstage can become quite intrusive if the sound is not carefully produced, and most shows benefit from a simpler layout IMO.

My idea is that you can't fill the stage with your chorus and delays if the other instruments haven't got the same "weight" and presence (apart from special, atmospheric parts), so a balanced sound becomes harder to achieve in my experience.

It also depends on genres of course: in order to play Pink Floyd some stereo sound is mandatory, while with any classic rock song stereo is something you can... avoid to afford

I have stereo by the mean of a camplifier + a 2x12 cab. It's somewhat (and sometimes) better than mono, but I don't think it justifies buying an additional DXR.
I like to delay one channel by 7-10 ms, it gives a pleasant effect but sound strange at the same time.

BUT :

When I use my setup with an additional clean AMP sent to one speaker, and a kemper dirty tone to the other speaker, it sounds AWESOME !!
I just wish the kemper could do that on its own. Once I tried to mess with the parallel path but didn't achieve anything worth of interest.

For live: consider how many/few people are in the right spot to get the benefit of a stereo spread. Also consider distance in this scenario.

Quote from Zappledan

Yeah, as I think about this more, I think stereo sound is best left to recorded music rather than a live venue. Thanks to all for the input.

This quite sums it up, Larry.
Although I'm really a fan of stereo guitars on records when I'm playing live I always go for mono.
I play with a keyboardist and another guitarist and I want to gear them and they want to hear themselves, too.
If I payed in a trio I think I'd go stereo though.

Stereo is great for home practise, recording and live through FOH. For band-practise and stage-use it is less useful because a proper stereo-image require you to stay in a fairly fixed position.

When using stereo signals live one has to be aware of potential issues that arise if the channels are blended. There are for example digital-mixers that offer channel-linking for stereo-signals that blend both channels into mono destinations, such as a monitor. Then you get issues such as phase-cancellation in the mixer and your guitar may end up sounding bad. If you play through FOH monitors prepare a rig with a slow L/R ping-pong delay and listen to the monitor. If you hear the delay signal from both sides in a single monitor you are dealing with a bad mixing console or a sound-man who doesn't understand how to deal with stereo signals. If that is the case you are best off switching the KPAs main out to master-mono.