I talked to a friend, a better player than me, the other day, and voiced my concern that the Speculo seldom seem to accomplish anything when I field her. I told him that I felt that the Speculo can devastate inexperienced players, but almost never manages to to real damage against a good player - they've learnt how to defend against impersonators, and how to deal with them. My friend agreed completely. This might just be me who's not very good at using impersonators, of course. I've had lists devastated by opponents using Fidays or Speculos in several games, but I've also, on other occasions, been glad that my opponent use them - a misplaced Speculo is perfect Protheion-fodder for Nourkias, for example. I do play Haqqislam too, and I've learnt the lesson there that the Fiday is better for burning orders from your opponent, than actually doing much - but he's also significantly cheaper to field than the Speculo. Is the same really true with her? Do you run Speculos often? If not, why? if yes, what are your experiences with them? Please note that I'm talking vanilla here. The Shaasvasti-exclusive minelayer Speculo is another story entirely.
In missions with zone control I'm always taking it, as it's quite easy to park it somewhere in a more or less safe place. In other missions, depends. Sometimes I feel like I have to take it just to make opponents nervous and spend time/orders to dug her out, so you can say that she's sort of indirect ARO, that forces opponent to spend orders, as if left unchecked, she can potentially get rid of valuable target. I think that BSG version is better than Combi in N4, for me it was the other way around in N3. with BSG and being already without impersonation you have good chances killing someone despite what he has chosen as his ARO. in vanilla for 32pts and 1swc there's a lot of good stuff, so there are options. I think this slot can be adjusted depending on missions/meta. Even if you're not taking her, enemy has to respect that you might have a Speculo and deploy accordingly. Gotta say, if Greif operator was 0.5swc instead of 1, I'd probably take him over her, cause you want someone close to enemy DZ to try to deal damage if enemy hasn't left anything for your long-range weaponry (e.g. Avatar), and grief is cheap and really disposable (it was a fantastic addition to OCF at the end of N3)
Speculo is incredibly useful in vanilla, I use it all the time and its in every list unless I have a good reason not to field it. Don't plan on it 'devastating' the opponent. Its not a 30 point, start in the right spot and kill everything in sight monster - that would be ridiculous. Instead, use it to remove key pieces or nip around the edges at exposed models. I like it as an efficient attack piece, for if the rest of my army is not built around attacking and I am forced to go first in a mission. Lets you do some damage without a huge investment and focus on other goals with your main force. Re: Speculo v Fiday, generally everything said here about the Fiday is correct, and the Speculo is worse at that job with the upside of potentially trading big with the monosword. Generally I prefer Fidays, especially that mines one.
There's a lot of utility in just being able to drop smoke in front of a visorless ARO piece too, the closer you can get the smoke the more board you open up for your short range weapons and specialists to advance.
I actually think the Minelayer Speculo isn’t all that. It’s just More Speculo - OKish but an experienced player will clear it easily enough, and it will tilt an inexperienced player even more.
The mine usually takes 2+ orders to clear out though IF something starts with LoF to it. More if they have to walk something over, which means it's a very efficient way to waste 1-2 orders from the first player's turn. If you are the first player, placing the mine so it's, say, pointing at the opponent's entire fireteam can force some nasty choices.
I don’t doubt that the Minelayer can be good. But I find it “Speculo plus”- It does what the Speculo already does, but more so. The extra SWC cost isn’t always best placed there and it can be very swingy as to whether it does good. I’m just not sure the extra cost over simply a Speculo is worth it.
I take one about as often as I take a noctifier missile launcher - not incredibly often, but often enough to remind people to respect them.
One of the biggest strength of the Speculo Minelayer is how versatile it is imo. If you go first, you can threaten ARO piece by placing the Mine in a way that it would trigger on their trooper. If you go second, you become a massive order sink for a single trooper slot. (Deal with the mine, Discover both phase, you can then place another mine, they need to finish you off because of regen) The regular Speculo is also excellent, but it doesn't offer as much flexibility and it's a lot less order intensive to deal with.