It looks like you are going down the same path I went through in the last couple years. I got a MOD 50 with an SL2 to start, the SL2 was disappointing (didn't sound high-gain marshall or 80's for me) so I was looking at mods to do myself.
I converted my SL2 to an SL2X and was very happy with the results!
Personally, after you change it to an SL2X, upgrade the capacitors to SOZO mustards or something high end for more tonal upgrade.
If you still aren't happy then get it professionally modded by Jaded Faith, Salvation Mods or Voodoo to get the tones you are after. It is a learning experience, but it takes a lot of time and resources to randomly swapping components to hopefully find the tone you are after. Have a pro do it and pay attention to which components were changed and that might give you a clue for future self-mods.
Keep in mind that you have a DUAL channel module, and those are expensive are more rare, so if you sell it, it will cost you much more to get it back. My advice is to keep the dual SL2, do the SL2X mod + capacitor upgrade, and then send it to a pro to get it further modified after that. It is REALLY nice to have a dual channel module when playing with a band where you need a medium gain and high gain with one sound, etc.
Reply or PM me with any further questions