I added a rank to my jet boots and now it seems to takes x3 longer to change flight modes but once at top speed I do feel I'm moving faster.

Its this a bug that the flight modes are taking longer to switch?

It's possible something beneath you is aggroing on you, but you are moving fast enough to outpace them so you aren't noticing it. I think that makes your travel powers not change speed modes, so it would appear it is taking longer to hit the next speed level until you lose aggro.

Just one possibility.

Its not agro, even in the safe zones I'm seeing it every time i switch on JB's

Nope, that's how it works.

You've got a faster top speed, but you spend more time moving barely faster than a walk.

I wish they'd at least let us charge the travel power to get past THAT part.