On thomann.de, DMX-controlled moving light fixtures (a.k.a. scans or
scanners) by brands such as Eurolite and Stairville retail for less
than 200 UK Pounds.  Sometimes people involved in lighting internet
forums dismiss these as a 'waste of money', but there are few
first-hand reports of either longevity or failure.

More prestigious brands such as Martin, Robe, High End and Vari*Lite
sell broadly comparable equipment for thousands of pounds.

I would like to know:-

Aside from normal lamp replacement, how long can I expect these low cost
fixtures to last before they malfunction?  This is considering 
careful use, about one day per month.

Models of particular interest are:-

Stairville SC250 PRO a.k.a. ACME iSolution iRock IR-7S
http://www.acmeco.com.tw/ir7s.htm#
http://www.thomann.de/thoiw2_stairville_scanner_sc250_pro_prodinfo.html

EUROLITE TS-5
http://www.eurolite.de/eur_artdetail.php?artnr=51785810&lang=E
http://www.thomann.de/thoiw2_eurolite_ts5_dmxscanner_prodinfo.html
http://www.ukslc.org/forum/index.php?topic=954.0

My research so far has included seeking out product reviews on retail
sites and searching these web forums:-
http://www.ukslc.org/
http://www.blue-room.org.uk/