I should point out the 10k resistor is in parallel with the cap to ground, not series and you are right, it is fairly specific to using the MAX4080 chip as the current sense to get very accurate and stable readings.
My prototype is designed to work with up to 50 amps output. I process my current readings so they end up as the amperage value to 2 decimal places. For example 1234 in a variable would represent 12.34 amps. I use that value in my MPPT algorithm and for display/data logging and other regulator functionality. The duty cycle is changed in 0.2% increments. It results in tracking that keeps fairly close, say +/- 0.2V to the actual MPP at most times, and doesn't hunt that much, which in my case is fine. For example, The MPP may still hunt up a few volts within 10 seconds if the sun came out behind a cloud, which to me is fast enough and leads to maximum extraction of power in a day. I don't do adaptive step size, for me that was unnecessary but I have read plenty of whitepapers that it's one of the best methods. To deal with low isolation, I have very low amperage resolution (10mA) which helps, though i'll admit if the power is down to within a few amps output level the active tracking may get stuck if it wasn't for the full sweep now and then, I could of course increase the duty cycle increment on the active tracking to deal with that if I wanted but It's all a compromise at the end of the day, there is no perfect method.
I generally agree with your comments on the sweep vs active algorithm, however the sweep algorithm can be quite impressive. I do a full solar open circuit to battery voltage sweep in less than 5 seconds, and for half of that 5 seconds its running a fine sweep very close to the MPP thus losing very little available power. It also finds the MPP with an accuracy of 0.1V
If you do all the maths it works out for two sweeps an hour I lose on average less than 0.1% of the available energy from the sweeps.
I believe the Morningstar Tristar MPPT uses even faster sweeps as it's primary way of tracking, so does the Outback MPPT and the Midnite Classic, though some of these have configurable algorithm options.
For me that small percentage loss from more than a couple of sweeps per hour is unacceptable. But I guess these big companies have to allow for all the different customer systems and forms of shading that might occur and can see that sweeping would be more reliable in some specific cases.
Having a sweep algorithm is also very handy to check your own active tracking algorithm. I can initiate a sweep instantly anytime which then provides the results on the display for confirmation that the active tracking algorithm is accurate. It's also useful to give the active tracking algorithm a head start when the MPPT controller is first turned on.
I too think reading how you are going about doing your design is interesting. Keep up the good work and posting about it.