Would I be sad if I sold on my Roland Boutique TR-09 TB-03 & SH-01, and instead spend the money on Eurorack?

Bit by bit I'm creeping toward having a Drum/Percussion row. Though when I get a Pam's Workout+Expander I would've planned to hook up the Boutiques up via midi if I don't sell them.

I'm also getting to the point where I can see selling few modules and replacing them with others is going to take place now I see which ones I use most.

I'm probably going to end up with something like this - ModularGrid Rack

I enjoy the X0X sequencing style, so if this was my system I would hold on to the TR09 at least. I take a hybrid approach to drums with a combination of euro and an RD8. The monosynth sounds are easier to replace in the rack, but something about the ease of sequencing with a hardware drum machine works for me.
But, I am of the opinion that it’s best to part with any gear you aren’t using. I don’t get sentimental about gear anymore. I know others here take a different approach. I figure you can always replace it if you feel like you made a mistake by selling it.

It is very enjoyable playing on the TR09 and TB03 together and as you say the programming is very easy, the SH01 could almost definitely go.
Maybe I should actually strip out what I don't use in the rack and see if I miss anything.

Fact is, since the x0x-box methods are all well-established, they've got a very real "performance practice" around them, to the point that you've got a huge user base that's VERY accustomed to how they work/sound/etc. So, should you run dry on ideas, it'd be quite likely that you could run across another x0x user who'd hit the same creative wall...and they'll have ideas that are specific to those devices that YOU can use.

Yeah, I built the Robaux LL8 which is great for x0x style sequencing very performable so its kind of just a matter of building in the percussion voices to go with it. Then I get Ratchets and Euclidean out of the DNiPro DOT.