Yeah, those Markbass models are VERY clean, but will blow the 3Pro out of the water with clean open bass and absolute volume.
You have two options IMO (other than buying the 3Pro, which is not light).
1) Buy either of the Markbass heads and invest in a VT pedal (there is a new model with updated features that was announced at NAMM, and the two originals are great also). It will get you that Ampeg tone while still being able to use either of those Markbass heads. Many TBer's who want the option to go from a clean, relatively transparent tone to Ampeg 'warmth and grunt' on the gig are using the Markbass/VT combination successfully.
2) Find a micro that has more of the tone you like right out of the box. The Ampeg micro's (PH500 and now the PH800 announced at NAMM) both have more ooomph than the 3Pro, and obviously, that Ampeg tone. The reliability has not been the best on those, but most that fail happen pretty much out of the box, and they will send you a new one. You might try the Aguilar TH500 also.... more fat, grunty voicing than the very clean Markbass heads.