To the OP,
I kicked around a ton of options in my head before buying a new front rest myself. I've had/used the heavier cast base rests in the past, but wanted to lose the extra weight but keep the stability. Therfore I wanted something that was ultra stable, well made & lighter for F-class use but was also at home on a bench. I also knew that I really liked the design, quality and performance of the 21st century front rest top a friend of mine shoots with too. Its all C&C aluminum, US made and has huge easy to use side owl ear knobs on its pinch plates unlike the sinclair and caldwell tops that have the tiny frustrating knobs. I ended up building an ultra stable, & functional front rest using the following peices. Total weight of the rest is around 8.5 lbs.
1) Sinclair liteweight benchrest base kit* (base, legs, post only)
2) Sinclair elevation wheel (boat wheel style)
3) 21st century front rest top w/edgewood bag & reinforced bottom upgrade.
4) Benchrite superfeet bases for concrete surfaces. 2.75 dia.
5) Set of farley legs from PMA tool. (not shown in these pics)
Of course you can use any protektor front bag style as well that will support your particular stock design the best. I got the edgewood however for a few reasons. First being they offer a 3 inch wide bag to exactly fit my MBR tracker forend which allows the gun to track smoothly and torque free. Second, they are high quality & made from both leather (sides) & nylon cordura (contact surfaces) so it allows the stock to slide easily upon recoil & even better with stock tape. Lasty, are super precise and hold their shape very well. The 21st century top is awesome, it was the best 85$ Ive spent in a log time, lots of quality for the $ spent & I really like the wide adjustment range the forened stop bar gives you. The benchrite feet are a must have as well, either for F-class style shooting or bench to eliminate your leg tips from wearing down on concrete benches or ripping up your shooting mats. The only part of my setup I sort of wish I had was a windage top to allow easier fine tuning. I may end up getting a windage top sometime in the near future, who knows.
Hopefully this helps give you some ideas on features that you'd like your rest to have.
Below are a few pics to show you a little better.
