Just playing sorcerer and I'm wondering... I just found the Full Field Plate with 62 Armour plus 77% Armour and +17 to Magic. Sounds pretty great, is it worth trying to get Strength up to 90 so I can use it or hand it over to my Rogue, who can more easily reach that Strength rating and is also a Magic-focused build?

There is no penalty for magic users to wear heavy armor. With a good shield (ideally, the Stormshield) and good Full Plate Mail, a sorcerer can reach an armor class that provides substantial protection. Traditionally, these were called "tank mages", and they could survive having enemies close to melee range, because their armor allowed enemies to miss often enough for the mage to cast spells to solve the situation, either by killing the target or teleporting away.

To your specific question, it depends on what armor class you can achieve and in what area you are playing. Consult Jarulf's Guide for the To-Hit rating of the enemies you plan to face, and judge from that whether your Field Plate would offer meaningful AC.

I think at the point where you grow to MAX strength and own decent jewelry to be able to boost your strength to 90 without remorse, this armor will be outdated for you because (if you want to play a tank mage) the 109 AC it provides might barely be acceptable in Nightmare but not anymore in Hell. Keep an eye out for Awesome Plates (can be 75 + 150%).

Certo che ne vale la pena,piu AC hai e meglio è,subirai meno attacchi in mischia e dagli arcieri nemici.
Con dei buoni gioielli anche il mago e il ladro raggiungono facilmente 90 di forza per potersi permettere una Ful Plate Mail.
Comunque l'obiettivo deve essere una maglia ancora migliore,l'Awesome Full Plate Mail,fino a +150% di Armor Class,preferibilmente perfetta,da 75 o poco meno

WE SPEAK ENGLISH HERE

Ok,sorry