Hi David
I went through similar decision making process jus recently. I was looking for a small, discrete messenger style bag to carry my A7R2 and maybe 2-3 lenses that didn't look like a camera bag. I ended up purchasing the retrospect 5, it fit the bill in terms of what I was looking for however there are a couple of "issues" that need to e considered.
The Pros
1. It's beautifully made, high end canvas construction, it oozes quality everything from the canvas used to the strap and hardware, it will last a lifetime, I'm certain of that. I purchased the pipestone colour which is an olive colour, looks great
2. It's super discrete, it doesn't scream "camera bag, no-one would know you are carrying expensive gear in this bag.
3. The interior is sufficient for a body and lens attached plus a couple of extra smaller lenses, I think it's perfect for a Sony shooter that uses adapter leica or ZM glass or the Loxia line of lenses. I can fit the Sony, Zeiss distagon 35 ZM, sooner 50 C ZM and 85 ZM easily plus extra batteries, cards and my cell phone, wallet etc.
Cons
1. The bag is heavy for it's size, I think a coupe of people already mentioned this however honestly it doest bother me that much, in my view these bags are over-engineered, it's heavy duty canvas that likely will last a lifetime, I can't every see myself wearing out this bag.
2. I'm not a big fan of the divider system they use, basically three sections, however I usually cary the Sony with the 35 Distagon attached lying flat on it's side, carrying it this way occupies 2 slots, leaving just one area of the bag for additional lenses.
3. I'm also not a fan of the dividers, basically 2 dividers that sit perpendicular to the length of the bag and divide the bag into three sections, they do provide additional dividers to further segment the section but these have to be install perpendicularly as well.
4. Although the strap is very comfortable ( it's wide, heavy duty ) it doesn't have anti-twist swivels so it a pain because you have to untwist the start to sling it over your shoulder.
All in all, I think it's a great bag for a walk around town mirror-less shooter who is looking for a great quality discrete messenger style bag that is small in size and fashionable at the same time. I think if I had to make the decision again I probably would have gone with the retrospective 6 just because it's a little bit larger and the ability to sub-divide sections.
