They are serious, as long as you don't try to exceed the practical range of the loads. I limit my shots to 75 yards, after that the KE drops off pretty rapidly.
I bought the CVA Optima Pistol as soon as they were available back in 2011. This was the first year and are now referred to as the V1, since the V2 replaced it a couple years later.
I posted about it back in 2011. Initial impression and the first range session. I also posted about the first buck I shot with it that fall. I have only shot Blackhorn 209 in it. It kills deer dead, and is extremely accurate. One hole groups at 50 yards benched are easy with the load it prefers. 200 grain T/C Shockwave, 80 grains by VOLUME Blackhorn 209, Nobel NSI 209 primer.
The CVA Optima Pistol can shoot the same loads as the Optima Rifles, however the short barrel only allows so much powder to burn. They recommend up to 100 grains of powder by VOLUME. The pistol grip is erganomically friendly, at least on the V1.
The Traditions Vortek Pistol has a maximum powder limit of 70 grains by VOLUME. Not a fan of the grip on the Vortek.
Here are a couple threads I posted back in 2011. They are a little dated, and Photobucket photo bombed all the pics.
Box opening and first range session.
https://www.modernmuzzleloader.com/...liber-pistol-thoughts-and-range-report.20984/
First hunt
https://www.modernmuzzleloader.com/...gr-bh209-200gr-shockwave-very-dead-8pt.21010/
This is the search I just did to find these, and there is plenty more information from other members in these threads. That'll keep you busy for a while!
https://www.modernmuzzleloader.com/...=relevance&c[date]=1317438000&c[user][0]=4801
If you have any questions, don't be afraid to ask.