Anything from a Sachtler DV12 to DV20 would probably be fine. I think a DV15 or 18 would be ideal for your setup.
Comparable Vinten or Miller tripods would be cheaper and also quite smooth. I would avoid the Cartoni Focus models if possible, especially the older grey Focus heads with the side-load plate - the side-load mechanism wears out over time, causing the camera to fall off unexpectedly.
I think OConnor tripods are probably out of your budget but if you can pick up a used 1030HD system, then go for it. Stick with 100mm ball systems. 75mm is too weak, and 150mm is overkill for your SR rig.
For the legs, I really prefer Sachtler/OConnor 2-stage carbon fiber sticks with mid-level spreaders. They are the same, just re-badged since both companies are owned by Vitec. Aluminum legs really start to weigh you down over the shooting day, and mid-level spreaders are easier to move around across uneven ground. So in my opinion, these features are really worth the extra cost.
With an SR2, with the battery + loaded mag, canon 8-64 zoom and a few other bits and pieces it actually handles it quiet well once you balance it and then set the counter balance. However, it really probably is pushing the limits. Also, there's a lot of plastic on it so i feel like it won't take much of a beating.
The Cartoni Focus HD is definitely a lot sturdier than the original grey Focus model. But I would still be very cautious about that side-load design with that much weight on it. Something has to give for such an affordable head. Cartoni's much more expensive Laser and Gamma models are fine. But at those prices, you might as well go Sachtler or OConnor.
This is a photo of the counter-balance buttons from the Sachtler Video 20-III (which I can't seem to find on their site.) Can someone tell me how those counter-balance buttons work? It just seems like hitting a button to adjust weight seems a little inaccurate...
I don't like sachtler at all. The dial system and switches to add and subtract weight, is a really bad system. O'Connor's system is far better and it actually works properly. Sachtler's system isn't nearly as accurate.
You shouldn't need a tripod with specialized counterbalance for a 16mm camera. My tripod doesn't have it and honestly, when I use tripods with it, I never think it's something I need. With much heavier cameras, yea it's very nice.
Counterbalance does help with light cameras. The force on the handle required to tilt stays constant so it's easier to operate precisely i.e. control the speed of tilt, and diagonal pans are also much easier. Less risk of camera hitting the sticks with the lens as well.
Of lightweight ENG heads, Vinten seems to have the best counterbalance. Sachtlers also have more counterbalance steps now, 25-plus has 18 and I find it easy to balance. But Oconnor is better here, of course.
The Sachtler counterbalance system pictured gives you 7 different weight adjustments with the different combinations of those 3 spring balance levers - not as subtly adjustable as the O'Connor system but usually good enough if you have some tilt friction engaged.
With Sachtler heads, you just select the counterbalance setting in the nearest range and use the tilt fluid adjustment to even it out.
It's not at elegant or precise as OConnor's continuous counterbalance adjustment, but it's much faster to adjust on the fly and makes the head cheaper and lighter, which makes more sense for the ENG and documentary genres that is Sachtler's bread and butter. The more expensive Sachtler heads like the Cine 30 have addtional counterbalance settings that make this a non-issue.
That said, if you pick the right-sized head for your usual payload, you'll be fine. It's always preferable to have counterbalance if you have a choice.