I have both the Seneca V and the 421, and I greatly prefer the 421. The Seneca is annoying, because it actually lets you overboost the engines, which never happens in reality thanks to the turbo's wastegate controller (as long as the mechanics have it set up right). Really annoying to have to listen to warnings go off, and make constant power adjustments on takeoff and climbout. Aside from that, it is a great looking airplane, but in my opinion, not as much fun to fly as the 421.

I haven't had any trouble with frame rates from either aircraft. Both are very cool in there own ways. Tons of repaints for both and a lot of fun to fly! Granted the Seneca is priced better, but I tell you both are worth every penny....!