Some new PV-analogues have been surfacing in the US over the last few months. Little is known about their safety or toxicity profile, or about their relation to alpha-PVP in terms of SAR (structure-activity relationship).
There have been some anecdotal reports on their effects, but very few. The one exception being a collection of reports on "PV-8" scattered across various forum/message boards; most of these claim it produces little to no results and is an overall disappointment. PV-8 is the 2-carbon extended homologue of A-PVP.
A 3,4 dimethoxy analogue (i.e. 3,4-dimethoxy-a-PVP) was rumored to have surfaced late last summer, but it seems to only have been talked about briefly. It could legally be considered an analogue of MDPV by federal law and in some cases fall within schedule I. It is very similar to MDPV in its structure differing in only an opening of the dioxole ring structure of the phenyl group. Its hard to say how this chemical would compare to MDPV in other respects, and there are seemingly no first hand accounts on Di-MeO-a-PVP.
It also seems that 4-MeO-a-PVP has more recently surfaced, but as is the case with the 3,4-dimethoxy homologue, there is little to no information available on its toxicological properties, potency, or effects relative to the parent drug.
The ring fluorinated homologue (specifically, 4-fluoro-a-PVP) has appeared and, other than APVP and MDPV, may just be the only chem in the clandestine-PV line with any staying power, with reports suggesting results are similar in nature to MDPV and A-PVP, with some preferring the fluoro. As with 4-fluoroamphetamine, 4-F-PVP seems to be corrosive to tissues, causing discomfort and possible damage with some routes of experimentation.Though pentedrone has been a known RC for a while, its methylphenyl homologue has been a more recent development in the clandestine RC world. Pentedrone itself still remains common as a designer stimulant, and although it's not a pyrrolidine based cathinone, it shares the pentyl backbone and a similar potency to PV (much stronger than methcathinone and active at less than 10mg). 4-methylpentedrone has been said to produce results close to those of the parent chem, and seems to have generated, for the most part, positive feedback. I currently have no information on its potency off-hand.