I'm a big fan of opening with tacticals at the moment - you can aggressively forward cap with your servitors, knowing that they will be shortly followed by Tacs from HQ and tacs via drop pod. You can have 3 tacs on the field super quick, primarily because you don't need a structure (bar HQ) to produce them, saving both time and money. Securing a forward point enables you to get a forward barracks relatively safely, saving a doctrine slot from Tip of the Spear, if you're so inclined.
The thing is, I don't want to spent stacks of power on armoury and upgrades - I prefer to go for a speedy landspeeder. That means I'm not investing in flamers/plasma (I tend to focus on countering those via a squad or two of ASM doing their best via disrupt and melee with tacs as needed) and then transition into Devastators for my shooting firepower in T2, again to save power.
Do you think it's viable to go fairly heavy into Tacs without also investing in flamers/plasma, or will I get caught out once my opponent "catches up" later in T1 and erodes the advantage of having 3x tac squads super quickly?