As long as the yeast was in good health at the end of the ferment, there is very little risk that the lager will not carbonate. The last batch that failed to carbonate for me was over 15 years ago, and it had more to do with underpitching a barleywine than anything else. OTOH, if you have the Safale packets on hand, it can't hurt.
And I like your second question - I've bought/made 4 systems over the years, and always had the feeling that the capital investments were not fully utilized... Current system is somewhat pricy brew sculpture co-owned by my brew partner. So do side batches represent ... infidelity?