Pro: Pedulla CS Mighty B string Comfy as all get out Versatile Even string response Excellent fretwork Well balanced Thunderguts switch is very musical bass boost, without being boomy or muddy. Con: Lot of maple, so kind of weighty. Not Spector or Stingray 5 heavy, but it's got a bit of heft to it. I don't own one.
I own the bolt on version and love it, when I bought it I A/B'd it against the Thunderbass and to me the bolt on version had more punch and a little more bite, they both have the same electronics so all I was hearing was the difference between bolt on and neck through. They have very flat necks which took a bit of getting used to for me at first since I was used to a more traditional radius. The string spacing is pretty wide for a 5 (19mm), I would have prefereda narrower spacing being that I mostly play with a pick, but I'm sure it would be a dream for a slap guy. The body contours are very comfortable and the bass balances almost perfectly on a strap or sitting down. To give you an idea of how much this bass and my Rapture PJ5 impressed me I went shopping that day for a Modulus or a Spector, I came home with 2 Pedullas. If there is any con to them for me it would be the extra wude spacing (like I said I'm a pick player) and the fact that they were so good they put a huge dent in my wallet.
Funny. The 19mm spacing is optional. You got two optioned ones! Normally, I believe it's somewhere around 17.5mm. I prefer the 19mm myself, though the narrower doesn't bother me (I do fingerstyle, but not much slapping).
Here's my ThunderBolt 5 fretless. Tons of mwah, tons of growl, monster tone. A great bass, especially with TI Jazz Flats on it. This one has the narrower string spacing on it, which I like.
I didn't even realize it was an option, but yeah like I said I just grabed them off the wall at a music store. Oh well, even with 19mm spacing I still love 'em to death. :-D
I've had a Thunderbass 4 and 5, and just got a Thunderbolt 4. I agree that the Bolt has a little more punch. These are just a very solid sounding bass. With the thunderguts switch, you get tons of meaty low mids. With the single tone control, it's tough to dial in much high end (using TI Powerbass strings helps add a little). I haven't played one with the bass and treble controls, I'd guess you get a little more control over the tone. On my thunderbass 5, I felt that the only con was the 34" scale B string didn't seem as solid as my other fives, on the fours I can't think of any real cons. To me, the Thunderbass/bolts are to instruments what Ampeg and Ashdown are to amps. You can pick it up and always sound great, you can't get a bad sound out of them.