I'm using multi-cell lights and consider them "pretty safe". But here's my approach to them:
Prerequisities:
- a DMM (almost any will do)
- decent batteries (I use mostly XTAR 2600, even some Trustfire "flames")
- good charger (for example XTAR WP2 II)
Safety measures:
- measure the voltage of batteries
- when you get them (trying to match pairs - and keep them paired)
- before charging (making sure they are not dead, but remember that 0V reading from protected is ok)
- after charging (check that they are not overcharged)
- before inserting them to flashlight (check that the voltages are equal, for me 0.02V difference will do)
- after use (if the voltage is way different, try to match a better pair)
- keep "known good" pairs together (and don't use them one-by-one in other lights)
- dispose (/recycle) any malfunctioning cell
In case of emergency (haven't done this for a flashlight, yet - but for RC car batteries), meaning that if you hear any strange noise from flashlight or it gets uncomfortably hot:
- try to turn it off quickly
- back off (or throw it to "safe" place)
- if noise stops -> wait some time, let it cool down properly, then approach the flashlight and check batteries etc.
Whether this is "too much attention" or not, well, it depends.. I like powerful multi-cell lights and am willing to take the above mentioned steps. Actually it doesn't even bother me at all.
But then again: I wouldn't suggest multi-cell lights for any new flashaholic. There's much to learn and enjoy this hobby even with single cells.
For a good, a bit floodier single cell 18650 light I would suggest KD C8. Great light, good value for money. Just used it as a bike light for my 20km ride during morning twilight. Suits well also that purpose. :)