Richardmr,
I won't get into the debate on which is better, because I have not attempted anything close to a controlled comparison -- I can't even offer an opinion based on my own taste, complement of equipment, etc.
I can say that I was a long-time satisfied user of a Helikon. The Helikon is now in a friends system and still going strong after several years of relatively heavy use. By a large margin, the Helikon is the most durable cartridge I have used.
I am currently using a Titan. This is a much better sounding cartridge than the Helikon. It delivers a bit more of everything that is special about the Helikon (terrific rendering of subtle harmonic relationships, lack of murky/muddled sound (not a Grado!), decent dynamics, etc.), and it significantly bettered the Helikon in terms of a seamless quality from the bottom-to-top of its frequency range (the deep bass sounded a touch disembodied from the lower midrange with the Helikon, in my system). I like a cartridge that delivers a lively, vibrant sound, and this is something the Titan provides while not being overbearing and strident.
As a point of reference, I also have heard and liked a Transfiguration Temper V (very smooth and natural), the top-of-the-line-insanely-expensive Allaerte (warm and extremely seductive and musical without being muddled and inarticulate), and the VDH Colibre (I am not sure I could live with the Colibre, but once you have experienced its incredibly dynamic and energetic presentation of music, one is tempted to take a chance).