OK, so, to reiterate:
MV5: ash, maple, SC's.
RV5: alder, morado, HC's
Valenti: alder, pao ferro, Sadowsky SC's, Sadowsky preamp
Alleva: alder, indian rosewood, all alleva guts, volume, volume, passive tone, treble boost, bass boost preamp
Now...
All four have this in common:
They all weight more or less 9lbs, play out perfectly, balance well on a strap or on your knee. They all have great feeling necks that are wide-ish, but not overly so, and have a nice amount of runoff room beyond the G and B strings. The Valenti's USACG neck feels a little narrower, a little shallower, and doesn't have that gracious amount of runoff room. Whether "that means it plays faster, or is a little bit of an irritant" is kinda up to you. If I play it first, I never notice that. If I swap to that second set or something, I kinda do. It's not at all a flaw, just a diff.
But, sonically, they're fairly different.
The MV5 is crisp, clean, and deeper than I thought an ash/maple might be. Kinda figured I'd have to roll a little bass in all the time; I don't. And loaded with the Sadowsky SC's it will just rip right thru a mix. The SC's sound really bright solo'd, but don't, at all in a live mix. Just cutting. Also, solo'd, the VTC doesn't seem to darken "as genuinely chocolately" as the Valenti. In a live mix, the VTC darkens genuinely enough. I love this bass. It rips and snorts and grinds when you lay on the strings, can sound quite modern, or, not, depending what you do with the preamp. Just ease along, and it delivers thick, clean, pure, driving fingerstyle that doesn't lay down for anyone.
The RV5: I don't care for the HC's. I know some do. They don't have enough mid push for me, and the highs seem to high and clacky compared to the SC's. It sounds "woodier" via the fingerboard vs the MV5's maple, which is to be expected I reckon. I'm waiting for single coils to be back in stock. She plays great, but she don't float my boat with the other three hanging around.
The Valenti: This was my fave before the MV5 arrived. She's a beast. Solo'd, the VTC really darkens things up in a more genuine way than the MV5. In a mix, they both seem to do about the same, though if you want to go all Family Man Barrett I tink this one still darkens up better. The fingerboard doesn't sound as woody as the RV5, nor as crisp as the MV5's maple. But you sure don't need to add treble boost with the VTC wide open to be clean and clear either; and adding a little treble boost can take it from edgy to mean real quick. I could, and did, do every kind of job with this bass before the MV5 rolled in. If this had a maple board, the MV5 and this would likely sound more same than different, but, the pao ferro on this spins it towards a little darker, a little softer, "a little nicer" vs the MV5's "mean sometimes."
The Alleva:
This one just flat out sounds more vintage and organic than the Valenti or MV5. I won't compare to the RV5 cause I'm just not an HC fan. While you can add some treble boost and get this one shinier, it's never gonna be the "chameleon" the MV and Valenti are. Adding too much treble boost starts sounding disingenuous and untrue to it's character...if that makes sense... It is what it is. I could take this to any job as well, but, I also take it specifically to some things I wouldn't take the MV5 to because of the Alleva's more organic/slightly darker nature.
That's probably enough of all that
as you asked if anyone noticed that there was a trend developing. 
