Looking for a more solid-feeling turntable (and maybe a new preamp)

Acoustic Signature tables are very solid, and heavy. Whichever model meets your price target should answer your need.

I have a Montana Neo, and am looking at their Double X Neo if I decide to downsize.

What is the Rega placed on and have you experimented with such?

DeKay

Some would say that VPI and Rega are opposite ends of the spectrum. Maybe consider some in-betweeners. Suggestions are Clearaudio and Pure Fidelity. Good options within your budget. 

I had a Helius top tonearm.....all kinds of headaches.....went back to the manufacturer a few times and I gave it up

Two major factors (at least) here: 1) Your arm mass may be a little low for the Dynavector's compliance. That will wipe out bass on a vinyl rig faster than anything else. 2) I have never been able to square Rega low-mass 'theory' with either physics or my ears, although I think arms like the RB-330 are great, VTA issues aside. 

Personally, give me some well damped mass, like VPI. My Prime Scout weighs in at over 40 Lbs and has a solidity of bass an resistance to footballs and feedback I've never had before. Newton's First Law in action: An object at rest tends to stay at rest unless acted upon by an external force. And then Newton's Second da Law kicks in: Force=Mass X Acceleration. Or, in this case Acceleration = Force/Mass. Increasing Mass reduces Acceleration (of the stylus) by external force. Rega argues that once in motion, higher mass takes longer to stop vibrating. That neglects two factors, it is harder to initially get the higher mass moving, and second, the damping of that mass, the 'Q' is a major determinant of how long that mass resonates.

For all its humble origins, MDF is quite well damped. Especially when layered with constrained layer materials. So are some composites like quartz/acrylic countertop. A plinth-sized piece of 3CM quartz/acrylic countertop would weigh upwards of 75 lbs if used as a base. If cut out to hold a DD motor assembly, probably 50-60.  A 2.25" (5.7cm) MDF plinth like my VPI comes in at 20lbs or so before layering with steel. And at a fraction of the cost of quarz/acrylic (water jet cutting and finishing aren't cheap). Add to that the 22Lb platter, and it's not east to get vibrating, and is damped enough to do so at a low level, low frequency and low Q.