Well, to be honest I can't recommend something so small as that. I realize that you have a light habit but the EGO Twist is probably cheaper (I live in the U.S. and I don't deal with foreign vendors) but the real reasons I recommend it is because the battery life on a small ecig is far less.
batteries are usually only good for 300 charges. After that the voltage drops permanently and they are recommended that you replace them (by the manufacturer) because over time your safety voltage regulation circuit on your lithium ion battery can fail and increase the chances of it catching fire (at least that is there thinking - to err on the side of caution). If you are recharging it twice as often then it will last half as long. The other reason the EGO C Twist is the best option is because with variable voltage it will give you precisely the vape you need, be it weak or strong. You can't do that on a standard, non-variable voltage PV.
I realize that this isn't what you wanted to hear, and I apologize for that, but it's good to examine your options. The only problem with my recommendation is that the EGO Twist is one long PV and it's the exact opposite in size.

Oh well I'm assuming you carry a purse which is better to try and fit these
devices than a pocket of some skinny jeans.
BTW: once a lithium ion battery has been sitting for years with no charge it is highly recommended that you do not try and charge them. Once they get below a certain voltage (usually 2.2v) they will go into a sleep mode. It is possible to "wake them up" but I am not going to go into it here because it can be dangerous (batteryuniversity.com will tell you if you really want to know). Once it reaches 0v the safety circuit dies and if you try to charge it there's a good chance that it will overcharge and blow up the battery. So that's why your old ecig is "knackered". The self discharge of your battery is caused by that safety circuit, so leaving it unattended for long periods of time is why it died.
Another reason is the SD Keyring as far as I can tell only puts out like 3.4volts. The EGO C Twist puts out 3.2 - 4.8v and is guaranteed to help anyone quit since they can dial in what they need. If they're having a hard day they can bump it up. You can't do that with a SD. You only got one speed. LOW.
Throw a E1-V clearomizer or a Vision Vivi Nova Mini on there (whichever is easier to get where you are) and you are good to go. The E1-V is the better of the two but you gotta do what you gotta do.