I can weigh in on this topic a little bit as I fly paragliders as well as paramotors (powered paragliders).
I currently own a 200cc Nirvana Rodeo unit and also second unit no name brand with a twin cylinder 200cc DLE engine in it.
The Nirvana weighs 34kg with full fuel (10litres)
The DLE is considerably lighter...about 26kg with fuel (holds less fuel and the unit itself is also about 6kg lighter than the nirvana )
The big issues for me are
1. thrust and how much one needs is heavily dependent on the wing and obviously pilot weight. My Nirvana puts out a lot of thrust...in the order of 65-70kg of it.
2. Flight time...with 10ltrs of fuel on board i fly for about 3 hours on average.
In terms of electric...it simply has to be a lot lighter or it's a waist of time. Some of the guys I have heard about who investigated electric love the lightweight but are very restricted by flight time...I have heard 15-25 minutes at best.
Finally one important thing...paragliders have accelerator systems. With powered paragliding wings, this system is comprised of a foot control (speedbar) and hand control (trimmers). On a reflex wing type (which the best powered wings are), activating speed system will quite often use all of the available thrust an engine can produce to maintain level flight, unless the unit is way over powered for the weight it's carrying. The reason for this is the dramatic increase in speed with full speed system engaged...on a lot of wings these days it increases from about 40km/hr to 65km/hr and on higher performing wings, up to 80km/hr...so it can be a massive increase in propeller rpm and thrust in order to achieve this. One may ask why engaging speed system on a wing should matter...because engaging speed system dramatically increases sink rate in order to also allow the wing to fly significantly faster. Paragliders only climb or descend by varying speed through the air. So you can't increase speed without also changing sink rate to overcome the tendency to climb...achieved by altering the wing angle and shape (hence the two types 1. speedbar - alters Angle of Attack and 2. Trimmers - alters wing shape)
I think the speed system is the real killer for electric...this severely limits the scope of wing types available and what pilots can do. Flying fast means high propeller rpm....rapid current draw on the batteries. This means heavier battery pack...which ends up being of no advantage over petrol engines...especially when one also considers flight time.
Ideally I would say this, electric needs the following min capabilities...
1. At most 20kg unit
2. Absolute minimum of 45min to 1 hour flight time at about 1/2 - 2/3 throttle
3. Thrust of 40-50kg at full throttle
4. Cruise speed of about 40km/hr at about 1/2 throttle
Until those goals can be achieved as an absolute minimum, they are pointless.