One thing to focus on with 1f. Yes it does produce more fouling. If your lube results in hard fouling that interferes with loading, you're using the wrong lube.
The fouling should be soft so that it shoves right back down the bore as you easily load the next charge. Olive oil or bear oil have both proven good for me.
I've never experienced any ignition problems for that fouling going back down the bore, mostly I suspect because it is pushed back down ON TOP OF the powder charge rather than around the vent or nipple. Then it's launched on the next shot as that one lays down a new layer of fouling.
You're mileage may vary of course, but for me any extra fouling is a non-issue, right there with any loss of velocity from the slower burn.