Im not comparing it to my in line 4 or a p twin but my single cylnder suzuki which can do much better than 80 mph? Not that i am really looking for massive speed just a bigger bike, the S40 or savage is really small, about 350 lbs. and although i am pretty small about 155 add my wife who is probably 120 and a bigger bike just seems more comfy and better suspension wise. i will have to check the specs on them all and do some more research, I certainly wouldnt have assume a twin 900 would be slower than my single 650 even if it does weigh a lot more, that vstar 950 i sat on looked so beefy lol.You should look up the hp and tq specs for the vulcan it's considerably less than the 650 motor on the bike you are talking about.
v-twin motors are not very efficient motors, at least how they are designed for the cruiser bikes. I'm a fairly big guy and I don't often find little women to ride with me so the 900 wasn't a good option for me.
As for the Shadows they have the same style of motor now, so their power output is a lot less than it used to be. The Stryker is a good bike. My friend had the 1300cc stryker and that had just enough power to make it enjoyable while not too much that it wasn't controllable. It's hard to compare v-twins to inline motors or even parallel twins because the motors perform drastically different.
Also the vulcan 900 struggles to get up past 80mph. It's kind of pitiful IMO.
If you are tiny and your passenger is as well it may not be a problem for you but it all just depends on how you like to ride. If you have problems with 2 up on a 600 or 650 you may want to reconsider a v-twin 900 and start thinking v-twin 1300.