We recently purchased the Coxmate SRT as a cheaper alternative to an NK, and so far have been impressed with the cox box and the excellent service from RowPerfect!
Unfortunately our ratemeter connection has been broken on our boat, so I haven't been able to try out the rating features yet, but will update when I have.
In turns of sound quality, the Coxmate is great. It fits straight into the NK system. We haven't fitted the mounting plate as this can only be fitted in one boat, but the coxmate sits quite comfortably at your feet so this hasn't really been a problem for me.
The battery life is much better than that of an NK, so we know we can rely on it for races! Recharge time is quite slow, but if you leave it charging overnight, it's fine.
The only problem we had was a dodgy microphone (a fault from the manufacturers which they have since rectified), but Grant super-speedily sent us out a new one and this is fine now!
I would definitely recommend the Coxmate as a great value alternative to an NK if you want more features for your money, excellent battery life and great aftersales service!Rating:

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Having spent most of my time with an NK system, I was impressed by a number of features of the Coxmate. First and foremost is the baseplate, which is easily installed and fits easily into our existing NK wiring loom. This takes away one of the major problems with other systems, which is that the pins of the plug leading into the amplifier can easily be displaced and leave you without rate, sound or both. The baseplate can also be angled which allows the Coxmate to be adjusted so that the screen is visible, rather than working on the assumption that every cox can see the screen just as well as another.
I found the headset to be more comfortable than that used by either NK or RowData. I tend to get rid of the strap and stick the mic in my cap, and the Coxmate headset benefits from being thin enough not to cause me pain or be inconvenient when I'm using it. Despite its small size, we found it to be much clearer than any of the other mic systems in use. It also uses a standard 3.5mm plug, which allows other options to be explored, such as using a radio from the coach or an ipod (to take away the boredom when marshalling). As far as I'm aware, Coxmate are the only manufacturer to use such a simple system.
Despite these advantages, and the massive battery life (in comparison to any other system) I have only given it four stars because of the need to press a button to shift between rate and time. Whilst this is not particularly inconvenient, it is not ideal and those with the money should definitely consider the SCT system which displays much more information on one screen. However, for those who don't see this as a problem, this system is absolutely the best on the market, beating the offerings from both NK and RowData by an absolute mile.Rating:

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Exeter University Boat Club: Jonty Faulkner Captain, wrote
I have been looking around for a while for a coxing solution. The NKs are outragreously expensive for what they are. And We've had bad luck with the RowData ones in the past. We are thinking "why not try Coxmate". Everything looks good about it, including the price.Rating:

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This product was added to our catalog on Friday 12 October, 2007.