studio strobes/monolights offer increased control
I disagree. My SB-800 goes from 1/1 to 1/128th. Control is not an issue. If more control is desired, increase or decrease space between subject and light source. Not important, IMHO.
Huh? How so? It cannot be WB control... becuase speedlights are dead-on consistent. I can also mix and match other speedlights from other manufacturers without issues.
A single setting remains rock steady until you really start to drain the batteries, but that for me happens wa above 400 pictres. I run out of card space before I run out of battery space.
Yes.

But if the question is a 200 W/s head vs a $90 Vivitar, you may be surprisd. A Vivitar or a SB-800 are in the 130-150 W/s range at full power. An SB-600 at around 110 W/s range is *less* than 1 stop of brightness away from matching the power of the DLite-2 strobe and that one stop is not a lot... and I can EASILY match the exposure by raising ISO from 100 to 200!

The Vivitar and SB-800s placed side by side with a DLite-2 will show near no exposure differences when both are placed at maximum power.
However... do you REALLY need maximum power? Well, as mentioned, if you are in a small area like a basement studio, that studio head with mandatory umbrella or softbox will take up more room and not offer any appreciable increase in light quality or amount. A small strobe on a stand has a considerably smalller footprint in comparison.
and a whole range of available modifiers.
Literally... there is no modifier that exists for a studio head that does not exist for a flash head... and if by chance it doesn't exist, one can be made "DIY" for next to nothing. My snoot is a ceral box cut to size and covered with gaffer's tape. My grid spot is a smaller version but filled with black straws. My softbxoes are 28 and 50 inch apollos, my umbrellas are anything from 32 to 60 inch silver or white shoot-through or bounce umbrellas.
I would not say that these are accurate points, except for the power... which as mentioned in a small area, a 400W/s DLite4 set to minimum is about 75 W/s and would be close to the performance of a speedlight near maximum and require rediculously small apertures in the confines of a basement. You are looking at the biggest apertures possible would be in the F/8 or smaller range. This makes things like bluring the background impossible and if that effect is important to your style (sincerely, it is for me), that limits me more than expands my choices.
So why not go for the 200 W/s lights at that point, wouldn't they work? Yes, and nicely... but the $$ investment for identical performance from a speed light makes them a waste of money, lots of money. Plus you lose portability too. They are not a good value no matter how you look at it... if you look at it from all angles.
I love the big power, I want to purchase some serious power and soon... but I also know that in an area smaller than a 20 X 20, that big light is going to be a hinderance more than a help to your creativity. One cannot get it low enough... unless you make three or four 5 X 7 foot diffusion screens and place them one in front of another... but again, that takes even MORE room in an already tight environment!
I suggest that the OP rent a single 200 W/s head and a 400 W/s head and see for themselves. Test things out and make your decision based on REAL LIFE experience. This is the best suggestion I can offer. I've shoot with the Profotos, I've shot with the constant hot lightsource and I have shot with the Vivitars and SB's... I know what they do and what works for me. Nothing beats even a few hours of experience in making an educated decision. A brick and mortar dealer will even likely let you test both lights out yourelf for a time and find out right then and there (if you do not want to rent 2 lights for a day).