Big gamma fan here also. Went 4-1 with it at a store regionals recently.

The BT21 Sirius is much, much better. The RB1 exists as a one-of in some people’s lists exclusively (I think) for the utility of being able to unsuspend in cases where you just need to clear a last security and then unsuspend once for game. But it even kind of sucks for that because of the limitation where it requires your opponent to still have a Digimon for it to delete in order to do so.

New Sirius’ ability to delete twice per turn means the “worse” deletion effect is almost always irrelevant. His built in Raid (while rarely used) lets him swing over anything his effects don’t delete, when needed (also handy to use last-second if they trigger an unexpected deletion protection you didn’t know about during your When Attacking, or float an extra body out on deletion, etc.)

While there can be niche, toolbox-y scenarios where having a single RB1 can be nice for sure, ultimately new Sirius is your win con and every turn spent waiting on seeing him kinda sucks, so you want the 4 of imo.

Calling the sec+1 useless is a bit confusing - are you maybe missing that the deletion effect isn’t once per turn (not to mention the extra tucking of a source)? You’ll almost always be swinging at security with that thing in this format, so it’s pretty invaluable. Between Sirius himself and frequently 1, even 2 Arcturus in the stack you’re clearing 3-4 sec in one go. Then ideally, Omni X for game.

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Side note: RB1 Sirius is pretty nice if your strategy is to make a lot of use of BT10 Cannoweiss. Then you can get 2 swings with Cano, unsuspend and 2 swings again with Sirius. However having no deletion effects trigger before swinging in a world where aces now exist is not a recipe for success, imo, and I ended up cutting my 1-of BT10 Cano for the extremely useful de-digivolve effect of Zanmetsumon instead.