I´m owning the Powerslide Next inlineskate. The fit of the boot is ok for me after widening the instep of the shell with a heatgun. In Bauer skates i´m fitting best into Supremes 6.5D, but missing the depth of Nexus-boots. The feeling of the Next 40/41(it seems that a lot of hardshell inlineskatesboots have multisize-shells with different liners) is a bit tighter in the heel and wider in the forefoot than my Supremes and shoudln´t be smaller. Maybe you could find a comparison between Next and FR boots.
I had been giving the triskates two chances. First try have been my inlinehockeyskates Reign Zeus with a 3x100mm 215mm frame which i had to downgrade to 4x80mm 243mm frame because of stability and acceleration issues and second the Powerslide Next with a 3x110mm 243mm frame downgrading to a 4x90mm 273mm frame because of stability, hillclimbing and stopping issues. The three-bigwheel-design has advantages like speed and maneuverability but you have to be a decent skater in good condition and skate on a skating track with no hidden obstacles. My hockey inliners are great on a clean and smooth hockey rink but not supportive enough for me to skate around my living area. Due to the lockdown i only can skate around on sidewalks, bicycle paths and in parks with streetcrossings, stones, little branches, bumps, curbs, kids, byciclists, dogs, cars and so on around. I could compare the 4x80mm, 3x110mm and the 4x90mm frames on my Next boots which are very comfy, supportive and reactive and the 4x90mm has the best mix of stability, speed, smoothnes of rolling and controllability for me.
If the wheels on your skates are spinning for some seconds than your bearings should be ok for skating around. The quality, size(bigger wheels have lower resistance), hardness(I prefer between 85A to 88A for the street) and condition of your wheels(completely or onesided worn) and the skating style(rolling on the inside edge and not on the flat) are more of importance for the speed.