I had been playing a standard, all-DC-15 trooper list with Obi-wan and Rex for this season and our Prime Championship. With the upgrade packs released, I am incorporating some of those minis into my list, and have some options.
1) The Clone Specialist is fantastic for the Republic. The action economy you get provides a higher rate of efficiency for your attacking units. Removing those squads is non-negotiable; however, I could possibly try only playing 1 Specialist squad. But, the support of two is a real boon to the Clones. I played them with Electrobinoculars, which means they generate 3 tokens in 1 activation. Since they're for support, using Recover to get the Specialist back up is not a huge deal, since you will still provide 2 tokens to share, or you Recover + another single action to set up the next round of 3 tokens.
2) Though I played the DP-23 last night, I had such a touch match-up against Vader and Palpatine, that they don't deserve to be graded on that performance. They both mounted 6-7 suppression from Vader and Palp's command cards, and thus, weren't able to do much at all (general weakness for Republic right now). I think these guys will be able to chew up infantry, which is why I'm hoping to find the optimal way to use them!
Last Night's List (791/800)
Obi-Wan Kenobi (Force Reflexes; Force Push; Tenacity)
Clone Captain Rex (Aggressive Tactics; Offensive Push; Recon Intel)
Phase I Clone Troopers (DP-23 Phase I Trooper; Frag Grenades)
Phase I Clone Troopers (DP-23 Phase I Trooper; Frag Grenades)
Phase I Clone Troopers (Phase I Clone Specialist, Electrobinoculars)
Phase I Clone Troopers (Phase I Clone Specialist, Electrobinoculars)
Phase I Clone Troopers (DC-15 Phase I Trooper)
Phase I Clone Troopers (DC-15 Phase I Trooper)
Alternative List 1 (797/800)
Obi-Wan Kenobi (Force Reflexes)
Clone Captain Rex (Aggressive Tactics; Recon Intel)
Phase I Clone Troopers (DP-23 Phase I Trooper; Phase I Clone Captain)
Phase I Clone Troopers (DP-23 Phase I Trooper; Phase I Clone Captain)
Phase I Clone Troopers (Phase I Clone Specialist; Electrobinoculars)
Phase I Clone Troopers (Phase I Clone Specialist; Electrobinoculars)
Phase I Clone Troopers (DC-15 Phase I Trooper)
Phase I Clone Troopers (DC-15 Phase I Trooper)
For this one, I really had to trim the upgrades from Obi-wan, cut OP from Rex, and the Frag Grenades from the DP-23s. However, the Captain added to the DP-23 squads means you will have at least 1 turn of no suppression or panic for these boys. That could be extremely clutch. Of course, this is a reaction to how they were pummeled last night with Suppression (both panicked; 1 killed by the Emperor, 1 panicked off the board). But, with Imperial heavy on Suppression and a lot of people playing those lists in my area, this could be a good idea, generally. Of course, they could go on the DC-15 squads, instead.
Alternative List 2 (797/800)
Obi-Wan Kenobi (Force Reflexes)
Clone Captain Rex (Aggressive Tactics; Recon Intel)
Phase I Clone Troopers (DP-23 Phase I Trooper; Phase I Clone Captain; Offensive Push)
Phase I Clone Troopers (DP-23 Phase I Trooper; Phase I Clone Captain; Offensive Push)
Phase I Clone Troopers (Phase I Clone Specialist; Electrobinoculars)
Phase I Clone Troopers (Phase I Clone Specialist)
Phase I Clone Troopers (DC-15 Phase I Trooper)
Phase I Clone Troopers (DC-15 Phase I Trooper)
This iteration really focuses on the DP-23s and getting them into position and hammering something. Sacrificing Electrobinoculars on one of the Specialist squads could be irrelevant since it is replaced with 2 Offensive Push upgrades for the same price, that, if not used, are shared with other squads anyway. This enables the DP-23s to be issued orders with Take That Clankers, have Range 3, Pierce 1, and move & shoot.
There are more combinations to play around with upgrades (I'd like to get Tenacity back on Obi-wan, at least), but these are the options that the Upgrades pack opens for Clones! In a world with limited unit options for the Republic, this adds some excitement to playing them and thinking about building lists.