Jez, here's what I do, and the rationale behind it, it may help you.
At home, on the edge of a badly light polluted city in the heart of the midlands, I have an observatory with permanently mounted telescope and the opportunity to image the samd object for weeks on end if necessary with pixel perfect precision. Narrowband imaging is very important to me at home, and it opens up the opportunity of moonlit imaging. At home I use a MONO camera. Unless the desired target is something unusual, short lived, or generally requiring short time on target. These may be comets, asteroids, supernovae etc, in which case I use a OSC or DSLR camera. Downside of LRGB imaging is the hassle of calibrating four sets of images, including taking flats through each filter, for each session. This process I find fiddly, tedious, and time consuming. LRGB images take a lot longer to process than OSC, require more discipline, more knowledge, and MUCH more disk space. The tortoise OSC catches up with the mono hare here somewhat. There is nothing more precious than time......
When I travel to dark sky locations, with a portable setup, and limited consecutive nights on one target, I take advantage of the darker skies and use my OSC. This way, even if I only get clear enough skies for one 10 minute sub, I still have a reasonable, true colour record of the target in question. Typically, when I travel to star parties, when I go with a OSC I get more useable results than when I have taken a mono camera. I am lucky that my imaging scope of choice has excellent colour correction, which makes OSC imaging possible. This is the UK, dark, clear, transparent skies are rare. I like to have the right tool available as the conditions dictate, and this may be a mono or a colour camera. As mentioned previously, there are compromises.
Aesthetically, colour images taken with a OSC camera always appear more "realistic", or natural to my eye. It is entirely possible, and is best practice, to calibrate RGB colour imaging by using a G2V star with similar colour to our sun. In many images however the colours can appear a little forced, although this is a personal opinion and preference.
I guess, what i'm getting at, is go for a mono camera, you'll need it in the UK. But if you can, get a colour camera too to really maximise your astro imaging potential.
Hope those ramblings help a bit. As you can see, the answer to your question is, "it depends...."
Cheers
Tim