I too have been researching this for months now. I've decided for 2012 I want to get a bike license, and I'm swaying between the Pulse Adrenaline, Sinnis Apache (same bike - different body panels), and the Sinnis Trackstar. I have read page after page of good feedback on the Pulse, but the Lexmoto is nowhere near as popular in the UK, so finding information is more difficult. Anywhere here is what I can tell you:-

Pulse Adrenaline & Sinnis Apache all use a licensed Suzuki 125cc engine built in the same factory as the Suzuki 125cc DR models (I think).
Pulse Adrenaline has weaker plastics than Sinnis Apache, Pulse plastics are painted and lack flexibility of Sinnis Apache's dyed plastics, which therefore crack the paint under flex.
Sinnis Apache has a polished alloy swingarm, whereas Pulse Adrenaline is painted black to match frame.
Pulse & Sinnis are both UK distributors of the Chinese firm Qingqi (aka QLink), and is seen as one of the highest standards of Chinese built bikes, with very high quality control and reliability of Suzuki branded 125cc engines.
Chinese motorcycle tyres tend to be quite poor in rain and are one of their negative points. Many replace these immediately if they want to use the bike in damp or rain.
Wiring can often be to a lower standard so make sure to check this. Qingqi bikes also arrive well lubricated and with valves setup correctly, which is often skipped by other inexpensive manufacturers.

The Sinnis website has numerous links to one of the distributor staff's 10000km ride on a Sinnis Apache (EXACT same engine as Pulse Adrenaline - just with different engine and gearbox casing).
Pulse Adrenaline is based on Suzuki DR125 which is a design Suzuki have been using for two decades. Anyway, thats all I can tell you. Will hopefully be buying one myself this year!

P.S. check out the ADVRider forum for a few inspirational topics for kitting out your bike. Also look for Carl on this forum he seems to be a ChinaMoto Guru.