I have mods from Pete (SL+), Anthony, VooDoo (Jose), DFriedman (HBE)
The PeteSL+ continues to be at the very top of my list- it has 800 on a switch (the other side is more of a scooped JCM2000 sound) and a 3 way bass cap that yields a ton of options. I love ZWylde, I asked for it and I got it in spades. The gain can be cut down to cool dirty tones, the bass cap is always adjusted according to material, room, cabinets, guitar.... this is a killer module! The Marshall faceplate and knobs are an outstanding bonus. Pete takes what you like about a module and enhances it's sound to a world class professional level.
Anthony's work is truly exciting...I was a bit hesitant to send my stuff so far away to -at the time- a virtual uinknown. But rest assured, he has many happy customers worldwide now and for good reason- he has a great service- delivers amp tones no one else does, and does it with great art work, solid communication, and reasonable turnaround time. I'm a huge Salvation fan-I have a few more on order. Anthony's clips are great and they sound even better in person. This is a great option if you're looking for a specific amp.
VooDoo Jose Mod- this is a cool module I picked up- inside the cage is a gain adjustment- very useful option. This mod does not need a boost if you're anti-pedal- it has tons of gain. Very quiet as well, surprising for the gain on tap. The low end is not as pronounced as modern hard rock and metal, but the clarity and gain is outstanding. In some ways it reminds me of the JCM900/2000 tones- which i like a lot, though that is an individualized assessment
DF Hairy Brown Eye: This mod has tons of gain- boost pedals actually diminish the tone! It is a gain machine, make no mistake- that dirty half driven sound is not it's forte at all. It has pronounced EVH type mids , so if you want a more modern tone perhaps the Black Eye is the way to go (never tried it though). This mod may sound beter on non Les Paul guitars- on my LP it is almost 'too much'. There is a some noise that accompanies the gain, but not enough to bother me much. This is a one trick pony compared to the others, but the trick is a good one.
I never heard a Jaded Faith (Rob) Plexi, but I'd like to, that seems to a growing fan favorite. Someone needs to post some clips of Rob's work!
Now if your SL+ is relatively new- 800 already installed- I've never heard that stock version.
All of the mods I have are clear upgrades and worth the money- it turns your mts into a whole new boutique beast. I am grateful that we have many options to choose from.
Hope reading this book helps!
-Ray