I went the same, but didn't want to return through Grdi graben, so went rather over Ovnov čir to Kokrsko sedlo. So, nice variant, you can extend it over Grintovec if there's time, will and energy left.
Briefly about the tour:
1. Suhadolnik-Taška-old hut: bp. Some gymnastics at the handholds, but overall fairly easy
2. old hut-Grdi graben-Dolci: maybe even the hardest part of the tour! Slope is very steep, fully exposed, grassy, slippery and secured only in a few places. Maximum caution needed, after wet strongly advise against. Dolci are one of those almost kitschy spots in our hills where one misses only a violet cow. Feels good knowing not everyone can get here (though no special issues over Ovnov čir).
3. Dolci-past bivouac-Kokrska Kočna: first gravel gully, then long annoying scree, then for me personally quite pleasant and easy climbing on rocks. Probably more issues on descent, but up it went really nice. Path secured only in one place, elsewhere free, but no special problems. Rock not super quality, but doesn't deviate from average in Kamniks and I don't know why Kočna got reputation of horrible crumbliness.
4. Kokrska Kočna-Jezerska Kočna: secured ridge path. Last July some protections damaged in places, but doable without issues. If memory serves, only one slightly annoying passage through chimney just before Jezerska Kočna. Path requires somewhat experienced hiker, but no really big difficulties.
5. Jezerska Kočna-Dolška škrbina-Dolci:
To the belly no issues, the belly itself more unusual than demanding. Follows quite high and steep gully just above Dolška škrbina (between junctions to Češka koča and Grintovec), which at least on descent properly nasty. About 20m straight down climbing without protections. One of key spots of the tour. At bottom of this gully branch to Grintovec, if energy left, extend the path. On to Dolci bit on easy rocks, then just full gas down scree. Enjoyment.
6. Dolci-Ovnov čir-Kokrsko sedlo: here too terrain steep and path narrow, but if no total stupidity, no problems. But the downside of this path extra 200m elevation from Dolci to Streha.
7. Kokrsko sedlo-Suhadolnik: bp. Choose one of the two paths (I took old one).
That's about Kočna from south. Must admit agree with domch. Serious and complete tour, but to me also very nice and recommendable. Most people recommend Kočna mainly from north, but I liked southern too. And also: even if doing connecting tour Kočna-Grintovec, recommend not start in Kamniška Bistrica, but at Suhadolnik, precisely because of possible shortcut through Grdi graben.