I run a ZF6 and wouldn't have it any other way, but that's just the way we like it around here. We have four manual trans vehicles and we just prefer it that way. Our BMW 540i is an auto, and despite being a powerful and great handling car, we find it boring to drive with the slushbox and plan on selling it soon.
Both the manual and auto trucks have advantageous and disadvantages, but I personally find this irrelevant and the only thing that matters is what kind of driving experience do you want?
From a practical perspective, we live in Colorado and drive in the mountains A LOT, both unloaded and towing, and I like the additional control it provides.
The ZF6 is hella durable, but its not bullitproof. Personally i'm on my 4th clutch, as my power level has grown I ditched a stocker when it wouldn't hold just a tuner, ran a SB organic single disc for years, upgraded injectors so i went to a SB street dual disc, and now i'm running a SB super street dual disc without the damping system. Clutches are what they are, you just have to pick the right one for your power level. As for the trans itself, mine was solid for 306K miles until i blew apart 6th gear while engaged in some highly aggressive passing maneuvers with the 250/100 sticks set to kill and a little shot of no2.
but... the upside here is that unlike an auto, any shade tree mechanic with some basic tools and a harbor freight trans jack can DIY just about ANY problem with the zf6 setup. hydros, no problem, clutch is a 5 hour job, I rebuilt my transmission myself in a weekend using $30 in harbor freight tools and $400 in parts. It was, honestly, pretty fun and easy to rebuild that.
I daily drive mine, and letting out that clutch pedal makes me giggle 10x a day.