I have been dabbling in rebuy events lately and would consider myself amongst those that plays loose early. I'm not a total psycho (don't have the bankroll yet!) but I have no problem shipping a fresh double rebuy with any suited ace, suited connector, etc. Strategically, the really loose method of play gives you the best odds
of winning the tournament as having a huge stack allows for a great many +EV moves that might not otherwise be there. Ultimately, it depends on your table during the rebuy period...being a maniac can cost you a lot of money if the rest of the people at your table treat the tourney like a freezeout.
Honestly, I think if you're going to play rebuy MTT's you should probably get in early and be fairly loose. Having a huge stack from the get-go is such a huge upside and really makes going deep easier. With regards to looseness, as you go up in buy-in that may change...I'm not sure the players in like a 50R or 100R are going to be quite as gamble-y as the 20R or lower.
Either way, I'd say play the rebuy tourney from as early a stage as possible and go for a big stack. You play these MTTs to take it down and that's what gives you the best chance. For BRM treat any rebuy tourney as at least 7x the listed buyin. Maybe more, depending on how you like to play...but even if you're going to be nitty in the rebuy period I'd think 4-5x buy-in is a reasonable price to assign a rebuy tourney.