This is summary of my own efforts so far with igniters. I have 5 different igniters, 2 gas and 3 electric based units and each one has their advantages and disadvantages.
Gas
These can work brilliantly and reliably for a while, I have even ignited Jetex motors with them. However, you have to remember to turn off the gas before lighting up or you can ignite the model or melt it if it is foam! Bin there, done that, got the T shirt!
The converted soldering tool (below) is however cumbersome in use as you have to ignite it separately with cigarette lighter, but great if someone else holds the model for you while lighting up and passes it to you in time to launch. Unfortunately mine started leaking gas quite early on.
The converted chef’s blowlamp (top pic left) allows single handed operation and has been great. However, I have had two as the handy piezoelectric spark ignition for the gas fails after a while and the seals also leak eventually. I need to buy a third now as my totally reliable back up igniter.
Electric
The cautery tool can work well but the single cell is wimpy and needs adapting to two cells. It has the lasting problem of keeping the motor exhaust crud off the contacts of the igniter wire. I am going to revert to wrapped connections again to see if that is more reliable. Last time out, I tried bending the wire at 90 degrees to help keep the crud off, but that needs further testing.
As a result of only having 2 cells on my adapted the cautery tool I made up my own 4 dry cell unit from a Radio Spares 4 cell carrier. In fact I have made two but the second has to remain a work in progress. The first unit has proved reliable once set up with new batteries and clean connections, I estimate I have achieved about 50 ignitions per set of batteries but that may well be an overestimate. A revamp is called for with some better means of protecting the igniter wire contacts from the crud without going to bulky terminal connectors.
The wire i use is 15 thou 28swg Nichrome wire for the 4 AA dry cell units. I keep the length of the wire beyond the terminal grip as short as possible, i.e. like 8 – 10 mm terminal to tip. 15 thou has proved sufficient to become hot enough and retain enough strength at this length to remain serviceable for extended periods.
As well as the crud problem I must look into rechargeable 4 cells at some point, as for the ‘cord zap’ type, I haven't tried them so cannot add anything.