I have been fortunate to have played in four orgainsed scrims (not all with the same team btw), all 8 v 8, and all on Emerald and Winterlake, err one on Cavern too.
My Opinion:
Team sizes - Even 8 v 8 on the curent maps felt more like deathmatch than tribes ctf, but that might be because you can dj from one base to the other on the current maps so there is no respite at all, i dont know. I won't lie to you i do miss the "space" of tribes one and two. Oh and i dont mean the long ass boring bits that happened sometimes in t2 base, i mean those little bits of thinking time you used to get.
Positions- As all old players will probably do we went with a semi-traditional setup on the first game. 1x ld sniper/repairer/tm, 1 x ld, 1 x Pod Defense/Chaser (on emerald this position just played ld/md), 1 x HoF, 2 x HO and 2 x cappers (1 HO'd sometimes). HO/BT was useless imho, it went down LOTS, but who cares if it only stays down for 30-40 secs. HoF was a no go, even with good support etc. Without a longer lasting shield pack, organised disc spam/gren spam and rp spam own you real quick. Oh and you last even less with a rep pack btw.
Cappers and ld seemed to have a fair tug'o'war, but all the games were definately more about flag stand-offs than chasing. Subsequent games i have played in we have ditched BT all together and just gone mo sensor/ld harrasment and we had much more success, which although it was still fun, as an ex heavy player i was kinda saddened. Oh and a few mines on the flag and 2 ld/md burnering/gren spamming it is way more effective than a HoF. MD buckler flag d is pretty win too. <-- the above is just my opinion, maybe other have found better ways....
Maps - None of the current maps are good competition maps imo, but who knows i thought that about minatour when i first played it and i ended up loving it, so..... What i do know is i want to see some bigger maps to bring back some "space", although this will probably make HO and BT even more useless. so who knows....
The Sensor System - Everyone who has read any of my posts knows i don't like this, but its for a valid reason. In all the scrims ive played it it has been necessary to take it down to cap/ho against competent ld/md/hof's who use their mini-map, but keeping it down takes serious man-power, as a one man in a rep pack can keep it/get it up in seconds. I won't harp on it anymore, suffice to say i think this element takes away far more than it adds to the game. ESPECIALLY in competition.
Conclusion - I had fun, it isn't really what i want in tribes, but it is fun, so i cant complain there, maybe with bigger maps i'll get the space i want, i dont know, but if it stays like it is, a DM with flags then i can't see myslef playing it as much as t1 and t2.
Disclaimer- it is early days, maybe IG will make enough changes either at release or after to make it a little more engaging, if not, it'll still be fun and sell a lot, it just wont be the game that occupies me for the next 3 years.