Define breaking the bank.
$80 for a Keeley seems like a worthwhile shot. I haven't played one, but like what I've read.
By "founding the edge off" do you mean the transients and dynamics, the tone, or both? The Smoothie is nice for several applications, but I wouldn't use it for a metal project, It felt too subdued for my industrial tastes. I couldn't get it to have any teeth at all. If you want to round off the tone of an overly bright rig, it's worth considering. If you want a brighter sheen to the tone, I'd look elsewhere, if I were doing this.
I've been pretty happy with the Seymour Duncan Studio Bass. I went through several compressors, and found it the right blend of compression and tone, for my needs. I wasn't looking for much tone "sauce" enhancement, but more transparent performance. The Duncan delivers that. The controls are easy, with a decent range of adjustment. The feature that wins me over is the "Blend" switch, allowing you to select a dry blend with full-range, lows only, or mids only. I find that helpful when searching for different sounds. I do wish it had a meter on it, to observe the amount of compression triggered, but that is not a feature. Pricing on the used (and even new) ones is pretty reasonable. Not $80, but not far away.
The Darkglass Hyper Luminal looks nice. The price is high. They have some bugs they are working out with certain power supplies not being compatible (a very small number of the supplies have issues delivering enough juice). The mA draw is around 250-300, IIRC. Make sure you have a supply with enough mA on tap, if you go with DG. I haven't heard the Bus or FET settings in person. The Sim (Super Symmetry) is going to be dark/warm sounding. I wouldn't use it for your application, having owned a Super Symmetry, unless you have an overly bright rig. However, the other settings seem to have nice potential. I'm considering checking one out.
I've had good luck with a Diamond. Again, not a cheap option (might break your bank, but might not). It has a distinctive polished vibe to it (smooth and glassy). I ran one with a Mesa M6, and was satisfied.
I'd rank your option and my suggestions:
1 - Keeley - Good reputation at a hard to beat price
2 - Duncan - It works (for me), it doesn't alter your tone as much as some pedals. Decent range of adjustments and a unique blend control. The price is nice.
3 - Darkglass - If you can afford it, it seems like a winner. It's new, so used ones are not plentiful.
4 - Diamond - Nice, but not cost effective, and a limited range of adjustments. Nice if you like what it does.
5 - Smoothie - Nice compressor, but too polite for metal (unless you were looking for a softer/darker Doom type sound), and not cheap enough to make it a budget friendly option.