can subwoofers make things worse?

It's all about what you want.

I believe the REL and the SVS offer easy to return trial periods. One is a sub-bass speaker and the other is a subwoofer. Get both of them at the same time and do your own side by side comparison. It's said they both offer useful phone setup support.

With its dramatic frequency roll off the REL is easily more forgiving of placement at the cost of articulately deeper frequency heft and air. ....Set it and forget it.

If the SVS is properly positioned within your room the flexibility of the remote controlled application adjustments will provide smoother speaker integration, EQ presets and volume control all from your listening position. ....Fun.

All the best with your search.    

@epz As you can see the HiFi community disagrees on subwoofers, choice and implementation which can easily lead the worse. Start with manufacturers that offer a simply return policy and customer setup phone support.  

When I put a $9K REL in my room the first thing I noticed is that its not really a subwoofer. In its manual titled Sub-Bass System the claimed a frequency response is -6dB@9Hz. Our best in room measurement began to roll off in the mid 30's, at a barely audible -6dB was 27Hz. Compared to the other subs in the room the big Brit's integration was the worst. So much for direct in room comparisons.

Even though I swear by my subs DSP, remote control and EQ presets. I prefer to use as little as possible which made corner placement out of the question in every room they've been in. Playing a low frequency test tone with a sub in the listening position to locate the rooms bass modes are where my two subs are positioned. 

A little hassle at first but when you get right you'll never go back.