Something no one's mentioned yet are the other factors that are involved during high speed riding. Obviously, the design of the bike & its areodynamic characteristics are going to play a big part. Whether you have a fairing or not, type of bars (drag, apes, etc), a windshield, the weight of the bike and it's engine size, etc...but one of the BIGGEST factors not being mentioned is the ambient air temp & weather conditions for a particular day.

Here in northeast Ohio - our weather changes literally by the minute sometimes. During spring & fall (ie, right now), I can be riding in nice soft warm air with 0 wind for a few miles - where doing 120 is a pure joy & smooth - and then boom - I'm in frigid gusty winds that beat the heck out of me if I even do anything over 70mph. Through the end of June & all of July - the air is usually hot - and high speed riding day or night is great. Outside of that 2 month window - and it's hit or miss for me.Having ridden several different bikes for many miles, I can say the dyna is definitely lighter and is more prone to being "uncomfortable" at high speeds - as opposed to most of the heavier HD touring models (I owned a Road King previously) or compared to a crotch rocket (I have a 750 Can-o'tuna (Katana) & often ride around with guys on Street Glides.
Everyone's comfort level is different & there are sooooo many factors that influence a bike's capability, power & handling at speed. Let's not forget the rider's own weight too! I'm 6' 185; put someone 50lbs heavier or 50lbs lighter - and they will have a completely different experience.
To answer the OP's questions - yes, I too agree that high speed on a dyna CAN be annoying, but not usually for me; depends on the conditions & how I have my bike setup. I love my bars. Love my seat. Tire size is great. Change any one of those things & my experience could suck ALL the time. I'm almost perfectly dialed in on this bike. No matter what type of bike I own, I know I will have to adjust & modify at least SOMETHING if not a lot of things, to make it "fit" ME perfectly, or near perfectly. That's just part of the game.
As for the backfiring/popping - again - that depends on several things. You need to ensure you have a proper tuning since you have the hypercharger, V&H's and PCIII, and also rule out any exhaust leaks. I know on cold days, I tend to get more deaccel pop than on warmer days, but nothing out of the ordinary. Heck - if you drive a stick shift car, put it in 2nd and drive it to high rpm's and let off on the gas. Do this over & over & listen to the engine. Is your bike sounding much different than that? If so - you need to either tune it better or find where the exhaust is leaking.

 

I just can't see doing any sustained speed over about 80 on a Dyna. It's a cruiser. If I wanted to do triple digit runs, I'd get a sport bike that was just getting above idle at 120 MPH.

 

MAX "cruise" for me is 75-80. Anything more things get a little windy!

 

The majority of roads around me, and northwest in general ( unless you're on the superslab) just don't support "cruising" at that speed. 70 up to 80-85 maybe. Too many curves, animals and just plain road conditions.

However I've hit well over 90 and the bike is still pulling strong. Backfiring from that speed when dropping rpms rapidly, would not cause me a concern. It's gonna happen, and especially if you let the throttle 'smack' closed.

 

Then..........................You Lose....BIG TIME.

 

Exactly.....