Part of the reason why I didn't mention cabs were cos some of the heads came with cabs while others didn't and it was going to complicate/make the post even longer so I decided to take that part out. But so far, my general consensus is that 4x10 would be the biggest I'd go. I like the idea of a 2x10 set up which I personally think is a good compromise between portability and being enough for small gigs.
Our band is sort of an Indie, Rock, Funk Rock sort of sound.
And as for the power output, I think 200w is pretty comfortable for practice and small gigs, which we are doing right now, however, in terms of future proofing and if we ever land gigs with a bigger venue, something like a 400w rig might be more suited.
I've been searching for GK rigs as well but so far in the Sydney used amp market, their priced a bit higher than the rest, from what I see right now.
Eden stuff, I have a lot of interest in. There aren't that many videos online, especially compared to some of the other heads mentioned, and I've noticed a lot of people mentioning that "Eden Tone" which makes me pretty curious.
Also, the Mesa head is an M-pulse 600.
Speaking in generic terms -- and not knowing what's available to you -- I would rather have two, 8 Ohm 210s than a single 410, whether 8 Ohms or 4 Ohms. A good 2x12 (preferably with the drivers vertically stacked, so it's tallish, rather than squat like most 410s) might hit the sweet spot in the middle for you.
Of the heads you listed -- again, without knowing which cabs might be attached to the deal -- if I had to pick one to be gifted right now, I'd probably take the Mesa M-Pulse. I had a Mesa Walkabout (300 Watts at 4 Ohms) and liked it, but wished it was a little tighter/more articulate and that it had a little more clean power -- both of which are supposed to be true of the M-Pulse 600 (lots of comparisons of the WA and M-Pulse on TB if you search). Note: I haven't played the M-Pulse.
I've known people who've used the Ashdown EVO heads and liked them a lot. My own experience with them is pretty limited (played one through a stack of Bill Fitzmaurice Omni 10s, years ago, and that combination was bright, loud, and punchy -- and played one once or twice in a store, where I can only say I liked the Evo more than the class D Rootmaster heads).
The Hartkes are supposed to be solid, clean-sounding workhorses -- my experience with them is limited, but I think I've liked the heads I've played more than the Hartke cabs I've tried. (To be fair, though, aside from their combos, I haven't played any Hartke cabs made in the last several years -- their most recent stuff might give me a different impression.) I've read varying accounts of their reliability/service on TB, but you could say that of a lot of amps. :/
My friend's had his WT550 for well over a decade. I know that he had to get the fan fixed once but, other than that, as far as I know, it's been reliable through regional and national tours, bar dates, sessions -- I wouldn't doubt that it's got over a thousand gigs on it. The Eden (like all of the amps so far, to varying extents) has its own, baked-in "voice", but has a super-flexible EQ, too. Been awhile since I played it, but, as I recall it, I'd say some bump in the low mids, a bit of scoop in the mid-mids, and kinda sweet and extended-but-not-harsh in the highs. Sorta warm and hi-fi-ish at the same time, if that makes sense. You could use it for any genre, but I think it leans more to the funky side than the rock side. Ugh -- super-subjective, squishy descriptions, but there you go. I actually quite like the combination of that head with his old Mesa Powerhouse 2x10 cab -- don't think that's a combination that either manufacturer envisioned, but the old Mesa cab gives the Eden a little grit.
Tone-wise, I'd expect the 330 to be similar to the 550 and other Eden amps (though hit up the Eden geeks here or on the Eden forum for nuances and differences), but it'll be down a bit on power. The EQ on the 330 is not as comprehensive as on the 550.
Never played the Markbass SA450, though I think some people here have lauded it as the best-sounding head Markbass has made. I have had an LMII, F500, and SD800 (two) from Markbass. All were reliable for me except the LMII (actually a Combo head in an CMD121P combo), though by most accounts the LMII are very reliable. I'd be concerned about being able to get the head serviced, should you have a problem -- might ask your area techs about that, or see if there's a Markbass service center handily accessible to you.
Trace Elliot heads have their fans (ever heard the saying "Trace Watts"?) and I was enamored with what I heard of them (via recordings) when I was younger. Actual experience with one is limited to playing through one of their 15" (I think) combo amps at a jam several times, six or seven years ago. The amps can do more than the scooped, slap-tastic sound that people commonly associate with them (on at least some of the heads, you can bypass the "baked-in" tone with a switch, but I'll leave it to Trace-heads to elaborate on that).
Afraid I haven't been much help with the descriptions.
Can you try any of these out before buying? That will help you figure out what you like and don't like.
Other than that, I'll say that the lower wattage heads (like the Trace) can do the job fine if they're paired up with a sufficiently efficient cab (or cabs).
Whatever you get should, if the cabs are any good, be a significant step up from what you're playing now. Since you are buying used (presumably, with the amps you mention), if it turns out not to be exactly what you need, going down the road, you can sell/trade/upgrade/refine your rig. Either way, you'll learn something in the process about what works and doesn't work for you.
