I have a 4-Stroke 500. I like it -- for me, it replaced an Eich T-900. I liked the Eich, too -- and the Eich had a little more power on tap -- but I liked the definition/feel/"hit" of the 4-Stroke more (and thought the 4-Stroke sounded more smooth/organic).
I've never owned a V4B, but I don't expect that you'll capture exactly the same vibe with the 4-Stroke.
Voicing strikes me as pretty close to neutral/flat within its passband (has nice, full lows, but not the super-deep/open lows of some amps -- the semi-parmetric EQ will allow you to boost quite low if you want). If you're familiar with the Thunderfunk TF550B, the Orange's voicing sits about halfway between that of the TFunk and am amp like the Eich -- more open, top and bottom, than that of the TFunk, but not as open (or as crispy up top) as the Eich. Less bright/aggressive more "round" than a GK 1001 RB, if that's a useful point of reference (though you can dial either some way toward the other).
Built-in compressor stays in the circuit and still has just a little bit of an effect, even when dialed all the way down. (Basic footswitch can be used to engage/disengage it entirely). Dialed fully down, the effect is subtle enough that you likely wouldn't notice it unless you A/Bed with it completely out of the circuit (footswitch); adds just a bit of thickness to the sound. Dialed up a click or three (as you dial up the compressor, you'll have to compensate by rolling down the master volume -- comp is a fixed-threshold optical design) and you start to get some nice harmonic content (along with compression, of course). Dialed up higher you'll get some grit in the sound, but I don't like running it that way (I rarely play with any compression beyond what I might get from a tube front end -- or, when using the Orange, beyond what I might get from zero to 2 or 3 clicks).
Four-band semi-parametric EQ is nice and flexible. I personally wish that the bands were voiced a bit wider, but that's just my taste with my cabs -- EQ is still musical and other people might wish it narrower or like it just as-is.
The Orange, at least into an 8 Ohm cab, felt more like the 700-800 Watt Class D heads I've played than the 500 Watt heads. That might be because (per John Dines of Orange), it makes something like 350 Watts at 8 Ohms.
Hope some of that rambling helps.
