The 125 is a good strobe, although the main reason I bought it was to use the optional slave sensor to attempt TTL with my 4040 - which turned out to be a bit of a disaster, I got so annoyed with it I just turned back to full manual (and I have one of the new corrected sensors not one of the old recall models).
I am in the odd situation whereby I use both an Ikelite and a Sea and Sea and there are things I like about each one over the other - the DS125 battery system is great, the battry disconnection system is fabulous, the aiming light is great, the recycle time is STUNNING although if you were using it with a digital camera the TTL function is very hit and miss (WA I am not sure about as I only really shoot macro to be 100% honest - although I am sure someone at at the
www.wetpixel.com forum could answer this question directly), my strobe came with an ikelite arm included which is a piece of junk, I also have an ikelite tray for the PT10 (came with the strobe kit) which is so well designed that when shooting macro all the strobe controls are underneith the strobe rather than on top where they can be readilly accessed - this kind of poor design forethought annoys when I pay $1000 for something (but thats the try design rather than the strobe)
I also use a Sea and Sea DX90 - weight is perfect - sea and sea standard arms are useless, use of AA (recharge) batteries is a great boon, recycle time is crap, size is small (which is good for my macro, manual strobe strength adjust system is simply the best for bracketing - lack of an aiming light can be problematic for night dives (I have to tape a torch to it if using it as a primary strobe - at present thought I just use it for fill in at a very low power setting on slave because the ike is better [for me]) , the system of connecting to PT10 by a fibre optic cable is simple but a pain sometimes, there is no diffuser supplied for the system when using the fbre optic link.
I have used them both as primary strobes (although I now use the ike as prim and the sea as sec) - the ike is easier to use but to 100% honest the 12 strength power adjustment levels of the Sea and Sea have given me better photos - the power adjustment is a great system because its so much easier to bracket using the strobe than fiddling with aperture controls on the PT10 - obvioulsy with all that bracketing I also have a lot more "throwaways".
Which is my preferred strobe of the the two - the Ikelite without a doubt. What would I buy if I had my time and money again - neither - in a perfect world I would buy a SLR, shoot slides and have a larger strobe/s on a wired TTL connection (I would probably also look like a young Robert Redford and have Selma Hayek as a dive buddy ;^) and dive on the Pelagian year round)