You would be probably upgrading or supplementing a 510 but it may be OK if you only vape 1/2 pack's worth of drags per day. 100mah is about 1 hour of moderate
vaping. Normal Joye 510 is 180mah. Joye 510 mega xl is better at 280mah but they are long - 128mm with a cartomizer (cartomizers are the preferred way to vape versus atomizer and cartridges it comes with). Manual batteries are used and recommended by most people here - not so easily damaged or killed by juice leaks (in fact Joye 510 manuals have a totally sealed metal threaded end - no hole into the battery) and easier to get a good hit. With a normal size 510 you would be charging a lot. But if you have a charging cable at work and a couple at home and have 3 batteries it may be OK. With manuals. And Boge standard resistance cartomizers are what I recommend for your favorite thinner juices. Slim batteries can only use standard resistance.
Ego is a 510-threaded fat battery model. 14mm diameter batteries vs 9.2mm for slim 510. The fat battery models have 650mah or more charge and can optionally use the hotter low resistance (LR) atomizers and cartomizers (which also use the charge up faster).
Ego-T comes with tank atomizers and tank instead of normal atomizers and cartridges. Many people have issues with tanks, some like them. I would only buy an Ego-T if you want the 5-click disable feature of its batteries for disabling/enabling the battery (so you can pocket it). if you buy Ego-T then I also recommend you buy a normal 510 atty and 510 drop tip, and a pack of blank 510 cartridges (not great for long-term
vaping but OK to learn on). And Boge cartomizers (standard resistance while learning to fill properly and keep them damp, then the LR 2.0 hotter ones if you want them).
Or buy the normal Ego (and a drip tip that fits whichever atomizer you chose, and Boge cartomizers) and later if you want to try tanks buy an Ego-T tank atty and tanks.
FYI - Ego and slim 510 can share standard resistance atomizers and cartomizers (like 2.5 ohms and higher). But eh slim 510 should not use lower ohms attys/cartos nor the Ego's fast charger cable (either can damage the slim batteries)
If you want a real Ego, only buy Joye or Janty brand, because some clones are crappy.