ACHiPo, you are discussing an SCLCR (rh) or SCLCL (lh) tool. This is the tool holder designation. This tool has a 5 degree positive lead so that it can both face and turn without moving the tool holder. It holds either CCMT or CCGT inserts. The former is used for most materials, while the CCGT inserts are usually used for aluminum. Both are positive rake inserts with two cutting tips. There are some tool holder sets that include a tool that will use the other two points but their utility is limited; AR Warner is one such company that offers these sets.
Typically, a 3/8" tool holder will take CCMT22.51 inserts for general work and a CCMT22.51 AK insert for aluminum. The CCGT has a very positive rake at the tip and is very sharp; at high speeds, this insert will rival HSS. Both are capable of heavy cuts taken at high speeds and feeds. If you must run inserts, this is probably the single most popular geometry in hobby shops. Cutting forces are lower than most triangular type inserts.
With that said, you have to remember that your Logan is a fairly small, light lathe with limited rigidity, speed and power. It was made to use HSS tools, not inserts. Just because you can use inserted tip tools, that doesn't mean those tools will work as they should; they will not. They will cut, no doubt, but not as well as they would on a rigid, high speed lathe that is capable of taking the depths of cut the insert normally requires.
As Doubleeboy said, you are far better off using HSS tooling that your lathe was intended to work with. HSS will cut well at the speeds and feeds you have available and the tool geometry can be tailored to reduce cutting forces to maximize the efficiency of the lathe. Yes, these tools are old school nowadays but then again, your lathe is old school, too. The only issue with HSS is that you have to grind them. This is not difficult but there is a learning curve.
Another option that many hobby guys take is to use inserts made from HSS. These inserts have no chipbreaker and are readily re-sharpened. Again, AR Warner is the company to look to for these types of inserts and tool holders. While they work better than carbide, remember that their geometry is the same as a carbide insert so cutting forces will be higher with them as well.
I own SCLCR/L turning tools and AR Warner tools as well so my opinion isn't a guess. These tools work, but HSS will work better in almost every case. HSS will cut with lower cutting forces and will finish better than any of these inserted tools. Moreover, the sharper cutting edge and geometry of a properly ground HSS tool will deflect less than an inserted tool so they are potentially more accurate. You don't appreciate this until you try to shave off 0.0005" with that tool; HSS will do it but carbide ... not so much.
Another option is a high quality brazed carbide tool. These tools can be sharpened to a very sharp edge and you can grind a nose radius on them to improve finishes. However, their geometry (flat top) is such that they do cut with higher cutting forces vs HSS.
For a light lathe with low rigidity, speed and power, my opinion for turning tools would be HSS, brazed carbide and then inserted carbide. For thread cutting, I would use HSS, although some sharp inserted carbide cutters will work nearly as well. For boring, I would opt for inserted carbide used on a solid carbide shank (this choice is complicated and beyond the scope of this discussion).
