I'd just look at how long it transmits for compared to others available (i.e. McMurdo). And the battery replacement interval - I don't think any of them have user replaceable batteries unfortunately...
Fairly sure it's just the McMurdo FastFind 220 in a cosmetically-different case. See also the Kannad Safelink R10 and the McMurdo Smartfind S20. The two brands are clearly the same company, or at least closely linked in some way.
These are pretty much the standard example of what a 406MHz PLB is.
Thanks for that info-the battery life on these is 24 hrs which is fine for me as normally I am within 30 nm of uk coast. It seems that SWMBO has "unknwn" to me got me one for Xmas, hard to keep sectets sharing a computer! Just hope it is not (say) Australian and I am unable unable to register it.