Your electrician could add a SquareD sub panel that would have the four SquareD AFCI breakers, fed from the GE panel with a standard two pole breaker.
AFCI breakers can be sensitive to certain loads. I've experienced problems with florescent lighting, power tools, and vacuum cleaners tripping the breaker.
Arc-Fault Circuit Interrupter (AFCI)
An arc-fault circuit interruption device is designed to detect dangerous arcing within the protected circuit, and open (turn off) the circuit to prevent damage caused by the arcing. It does this using special circuitry to analyse the electrical characteristics of the circuit, looking for characteristics that match specific pre-programmed values. If the AFCI detects suspicious goings on, it opens the circuit.
AFCI breakers are typically combination devices, meaning they also provide similar overcurrent and short-circuit protection to a standard breaker.
Installing a combination AFCI breaker on a circuit containing knob and tube wiring would be a great idea, and could potentially prevent a fire.
Ground-Fault Circuit Interrupter (GFCI)
Ground-fault circuit interruption devices are designed to detect ground-faults, and open (turn off) the circuit when a ground-fault is detected. They work by using a current transformer (CT) to detect current imbalances between the ungrounded (hot), and grounded (neutral) conductors of a circuit. This blog entry might help you understand how GFCI devices work.
GFCI breakers are typically combination devices, meaning they also provide similar overcurrent and short-circuit protection to a standard breaker.
Installing a GFCI breaker on a circuit containing knob and tube wiring, probably won't provide any benefit. GFCI devices are designed to prevent electrocution, not to protect the wiring.
Combination AFCI GFCI Circuit Breakers
Circuit breakers that provide AFCI, GFCI, overload, and overcurrent protection are becoming more widely available. If you can find them for your panel (and afford therm), these would be the best option.
Best Answer
You have it easy, since they added the GFCIs near the panel
So they did "my trick", which is install a junction box right next to the panel and use GFCI receptacles rather than GFCI breakers. There are two reasons to do that, #1 GFCI receps are way cheaper than breakers, and possibly #2 can't get GFCIs for obsolete panels. For instance Pushmatic is the best consumer panel ever made, but no GFCIs available for it.
So with the hard part done, an AFCI upgrade is a piece of cake: Swap the GFCI recep for a GFCI+AFCI recep.
That was easy!
But before you do that, look closely at the existing "GFCIs" as you call them. The "last guy" was pretty smart, and may be way ahead of you. They may already be AFCI or AFCI+GFCI deadfronts.
By the way, they don't have to be deadfronts unless they power kitchen, bathroom or laundry room. Feel free to use plain receps there for all other circuits, just pinky-swear you won't plug - no I'm kidding. Feel free to plug in anything you want.
GFCI's provide partial arc-fault detection
Generally we're interested in 5 kinds of arc faults:
The first two, parallel arc faults to ground, are easily detected by a GFCI because they are, after all, ground faults. In fact most AFCIs detect those by having a weak GFCI detection right onboard - that's why AFCIs need neutral.
Of course it's hard to have a parallel conductor-to-ground fault if you don't have ground. Assuming you don't have ground. A lot of older wiring used metal jacketed cable, which provides varying degrees of grounding (certainly good enough to trip a GFCI)... and some uses metal conduit, which is an approved grounding method today.