Mutt, saw your post over in the What's Coming and Going thread, figured I'd drop by to see if I could help out!
The Pork Loin is very transparent with no loss of bass. It can go from full and saturated to quite nasty.
Voodoo Lab Sparkle Drive. Basically a TS808 with an added clean mix. I love it!
I have both of these, and I sent my Sparkle Drive to Keeley for modding. Both are nicely transparent and keep low end well (even before modding for the Sparkle Drive). Both are darn good at low-gain overdrive sounds in original form, and both can get pretty darn crunchy. After modding though, the Keeley
really shines... twice the gain available and even better low end response than stock. More "open" if that makes sense, but a little more harsh than the Pork Loin. I use the Pork Loin more for "everyday life" on my board (but NOT as an always on pedal) and the Keeley for stuff that calls for more medium-to-high gain crunchiness. When I play Slang (Jaco), the Keeley Sparkle Drive is my go-to, without a doubt. It pretty much nails his overdrive/distortion sound at 2:19 (on the album version) or in
this live vid of the same song at 2:05 (but it's not the best recording).
Both are GREAT pedals and I won't be getting rid of either one. I think you'd be quite happy with either if you're looking for transparent, and the Keeley mod is absolutely worth every cent.
Just for kicks, I've also added a clip of the Hartke Bass Attack. Not really that transparent, but it has a great, beefy low-gain crunch and can get absolutely
HUUUGE. Seriously, I bet this thing could eat speakers for breakfast! On the last section of the clip in particular, I still could've added low end and Level was only at
2!!

I won this one from Larry Hartke himself via Facebook, and was
completely surprised at how much I like the sound.
I also have a Sansamp Bass Driver and owned/sold an HAO Rust Ride. Unfortunately, no clips of either of these.
All that said, I'm good in the "Transparent Overdrive" department which is why I ordered the Catalinbread SFT. I was specifically looking for a non-transparent overdrive... Old-school Fliptop flavor in a pedal that can also do low- to mid-gain crunch.
Enough blabbering, on with some clips!!!
Hope this helps!
5sg.
Pork Loin
various drive settings
Voodoo Labs vs. Keeley Sparkle Drive
Light Gain
Voodoo Labs SD
Keeley SD
Full Gain Blended
Voodoo Labs SD
Keeley SD
Full Wet Gain
Voodoo Labs SD
Keeley SD
Keeley SD - Gritty
Hartke Bass Attack
various gain settings