I'm an early adapter of the PW TT5 (I have several of them, didn't buy the TT1 because of the less convenient battery, the TT5 takes simple AA's) started buying my first units when they became available in 2009 (?)
Like them very much, despite the high price tag (although that has been next to constant since the introduction over here)
With regards to that price tag, at the time of their introduction there were no cheap, Chinese knock off, alternatives, so that simply was something that had to be taken accepted
Use them in TTL and Manual mode with the AC5 zone controller, and a SU800 (the original CLS infra red commander unit), so switching between Manual and TTL is, if desired, a piece of cake.
Ditto with setting the 'correct' power output (in Manual mode), and getting the exposure (in TTL mode) correct ( when shooting in TTL mode you can on top of the AC5/SU800 use the in camera flash exposure compensation function to fine tune that - I use the TT5's with SB800's on my D3 and D800's for event and catwalk - )
The reason that I use SB800's instead of Pro Foto's is similar to why I bought the TT5's, Pro Foto's simply weren't around yet at the moment I needed/started buying powerfull TTL flashlights (used Metz 60CT4 on my film camera's and older DSLR's)
That said, major considerations for me for not 'upgrading' also were/are the considerable difference in overall price, bulk/weight, and reliability of the TTL metering.
A 2 heads Profoto B1 location kit will set me back Eur 3569 in the Netherlands, on top of which I will also need to purchase an Air Remote unit for an additional Eur 349
At the moment I have, bought over the course of something like 8 years, 6 SB800's for about Eur 1200, 6 TT5 for about Eur 1100, an AC5 for Eur 65 and two 2 Godox 960 powerpacks and (4) cables for about Eur 360, so in total still quite a bit less, and since purchased of a longer period, much less strenuous on my finances.
And of course a single B1 weighs in at about 3 kg
The Nikon TTL is next to flawless as far as my experiences are concerned, with plenty of fast and easy fixes/options for further fine tuning just in case.
While the compared to a B1 lower output per speed light is not a real world problem for me (even my 500 Ws Bowens studio units I never use at full power).
And if I do need more power, I just add another SB800 (I at occasion have shot very badly lit catwalks shows with 4 SB800's/TT5's and additional PB960's mounted on a lightstand, enabling me to still shoot in TTL mode despite despite the 100 feet long catwalk)
Also just one SB00 can be taken along as just a small 'extra' in a small camera bag together with a camera and a lens, eg when taking a camera along 'just in case' or to a intimate family event like a birthday (not everone wants to be the party pooping 'uncle with the big camera, lens and flashlight') and of course if things do break down, I have plenty room for just picking another/spare unit (flash and/or remote)
Don't use the SB800's with fresnel adapters like the Better Beamer, so can't commend on that
But that said, he 'spread' of the light of a SB800 can also be aimed to a smaller area (just disable the 'zoom' function of the flash, and manually fix that at 105mm), and I also always have a couple of Flashbenders in my bag when I take a 'full' f;ash set up with me.
The 'start up' procedure for a speedlight/TT5 set is pretty simple/basic (just top to bottom, first the speedlight - that is/should be mounted in the hotshoe on the TT5, then the remote, et voila, you're done)
I have read very positive reports on the Phottix Odin units, basically do the same as well as the TT5's (definitely would consider them if I were to start from scratch today)
If you are 100% dedicated to shooting in Manual Mode, I would also recommend to just buy the 'dumber' PW units like the PW Plus III etc (but you teh allso would not need to invest in a Pro Foto set as well, even a golden oldie like the Mezt 60CT4 in manual mode would do then)
My 2 cents