It was my first OD pedal, and although I've gone from TS9s, to AnalogMans, to now my BYOC TS. there's been one on my board since the beginning. I still probably use it the most. Its in my Tim's loop, so always stacked with that slightly dirty boost.
Astrotone is so good. so much range when using your guitar's vol knob. and if you have humbuckers with separate volume knobs, even more sounds. i crank the fuzz full and tone all the way ccw and let 'er rip.
i've had a microvibe for 10+ years and got the JHS mod about 5 years ago. its a great improvement IMO. expanded range both in terms of intensity and speed. overall frequency response is improved as well, but it still adds some color to your tone. sometimes it sounds better at less than 9v, so...
i got the mod done about 5 years ago and love it personally. it increases the range both in terms of intensity and the speed. i find it plenty throbby. so if you like the vibe already, but you just want it to be a little better overall its probably a good move.
I can't imagine not having both! I run the Tim on 18v and put a TS clone in its FX loop to use those in conjunction. I love the Tim stacked with the Yellow side KoT, but usually use the red side on its own.