I just spent the whole night listening to music on my VTF 2.5. I played good mix of music from rock, country, pop, etc.
There was plenty of midbass and "chest thump". This sub is known to have larger amounts of midbass vs the SVS PB 2000.
I think the problem here can be one of two things.
1) you may have some settings issue. Make sure the crossover on the HSU is turned OFF (out position). This is why I was asking for a picture of the back of your sub so we could see what all your switches and dials are set to.
2) You may just be accustomed to/prefer subs that have a large hump in the midbass frequency.
For scenario #2
above I had a Klipsch 12" ported sub for a few weeks before the HSU. It was designed to provide a nice bump in output between 50ish-90ish hz which gave the impression that it was powerful and loud. The HSU is designed to play "flat". Meaning to say the frequency response should be even throughout a large spectrum. It took a little while before I could get my settings right and understand the way I was processing base in my head.
IMO there is nothing wrong with each design philosophy. It just caters to different crowds. Even if your issue is #2
the HSU should still be able to provide plenty of mid bass punch so I think there is still hope for you.
I still think we should have a closer look at all your settings.
1 other thing. Try flipping the phase switch on your sub. If you say you can barely tell a difference when the sub is on or off this may be a symptom of your sub and mains being out of phase. This actually happened to initially when I accidentally bumped my phase switch thinking it was the EQ switch.