Another Slingshot or Velocity question

I also have this posted on FM, so for those who frequent FM and this site my apologies for being annoying.

I know this subject must have been beaten to death by now, but with the tremendous variety of equipment out there I figured I'd ask for advice yet again on which of these would be a better fit for my scenario.

I already own a Lowepro Pro Mag 2 as my basic "hold all my stuff" bag. It gets the job done okay. I've been looking at the Slingshot or Velocity series as my carry around bag, expected to handle at max my XTi, 70-200 f/4 IS, 17-55 f/2.8 IS, and 100 f/2.8 macro plus 430 EX. Enough small room for an extra battery or two and some filters etc. The usual small bits.

In looking at the Slingshot, what bothers me about it is the sense that I would not be able to swap lenses without having to take the bag off, set it down somewhere, and then zip open the flap to access the lenses. It looks like if I tried to do that while the bag was swung over in front of me the lenses would fall out. I saw the post here which shows the inserts rotated 90 degrees, and it looks like it might work. But in that arrangement I'm not sure if it will hold my listed items.

The Velocity series, OTOH, looks a bit more traditional from being able to keep the bag open while it's swung around to switch lenses and whatnot.

The other part that bothers me about both is that - while maybe a Sling 200 and Velocity 8 are both big enough to handle the 70-200 when mounted - is either bag able to hold say the 70-200 and 17-55 loose while I have the macro attached and in the bag? I've tried some bags that work fine with the longest lens - as long as it stays attached to the camera. It seems that sometimes when you start moving the big lenses around all of a sudden the bag doesn't quite work as well.

Or maybe something like the Kata H-16 would be a better bet in my case? I've read on where those side pockets can hold the 70-200 pretty readily. Or even a H-14 could, but I'm not sure it's big enough for the desired load-out.

Advice appreciated.

If you're wanting to change lenses without having to put the bag down, have you looked at the Flipside 300 for example?

Amber, I guess I'm having trouble picturing how that would work. As a backpack type design, wouldn't I have to remove the bag in order to access the contents? I was hoping one of those clever swing-to-the-front designs would work.

(I see there's a product video link, which may explain things, but that sort of content is blocked where I work.)

Ah, I see how it works now. Nice idea!

It does take the video to conceptualize the bag. I had the same problem when it was first described to me. Then I thought "but won't it fall forward?" It is well designed so that the base of the bag is somewhat rigid, and the zipper doesn't go all the way down, so it supports itself on your waist with just the waist strap. While you have to slip off the shoulder straps and rotate it around to your front, it's a really slick design.