I have had a Multiplex Cockpit SX R/C set for almost 2 years now and I have used it for many hours without problems so far!
As someone else said the instructions are for aircraft use only, but then I have never seen any 40mhz 4+ channel sets which were any different! That said though the instructions are very clear and there has been several articles in the model magazines on how to set up these Multiplex sets for model boat use, mixers and the like. I have filed away copied of these articles with the Multiplex handbook, although as I am now almost 100% an R/C yacht operator I am not likely to need them. The TX/RX cover all the standard 40 Mhz frequencies ie. from 40.665 to 40.985.
I bought mine as I already had umpteen 40mhz receivers (with crystal type) and the Multiplex TX will work perfectly well with them. Equally my old Hitec Focus 40mhz 4 channel TX works equally well with the Mutiplex RX. If you only have 1 or 2 models then a 2.4ghz might well be a better bet, although I wouldn't want to put a £60 RX in a Club 500 model, but maybe that's just me being over cautious! The Multiplex TX has a slightly more quality feel to it than a Futaba 2.4 GHz TX to me at least, although the Futaba seems to work fine.
The standard TX aerial is a bit long, but the alternative stub aerial works fine and gives me all the range I have ever needed. You can turn the TX stick ratchets/springs on and off using a torx key, which is clipped to the back of the TX. For yachts I use a ratchet on the left hand stick, but when I raced Club 500's I simply set it to a sprung centered stick for the throttle. The TX requires a 3 pin DIN plug for the charging lead which is a bit of a nuisance, but you can get these plugs by mail order from Squires in Bognor, if you can't find one locally.
There are 12 model memories and they can have a 6 alpha/numeric character description and there are various timers which you can set for model runtime and TX on time etc.
Victor g7tmu
